Pattern formation method

ABSTRACT

A resist material comprising (a) a terpolymer, (b) a photoacid generator, and (c) a solvent has high light sensitivity, heat resistance, adhesiveness, resolution, etc., and is suitable for forming a pattern of rectangular shape.

This is a divisional of application Ser. No. 08/407,611 filed Mar. 21,1995, allowed.

BACKGROUND OF THE INVENTION

The present invention relates to a resist material used in theproduction of semiconductor devices and a pattern forming method usingsuch a resist material. More particularly, the invention pertains to aresist material used for forming positive patterns with ultravioletlight, especially deep ultraviolet light with a wavelength of 300 nm orless, for example, KrF excimer laser light used as exposure energysource.

With a recent trend toward high-density integration of semiconductordevices, there has been rising call for shortening of wavelength of theenergy source of exposure means used for fine working, particularlyphotolithography, and now use of deep ultraviolet light (300 nm or less)and KrF excimer laser light (248.4 nm) is seriously considered. However,there has yet been available no high-utility resist material suited forworking with light with said range of wavelength.

Dissolution-inhibiting type resist materials comprising a polymer withhigh permeability to light with a wavelength of around 248.4 nm and aphoto-sensitive compound having a diazodiketo group in the molecule havebeen developed as resist material for pattern formation using KrFexcimer laser light or deep ultraviolet light as light source (JapanesePatent Application Kokai (Laid-Open) No. (JP-A-) 1-80944; JP-A-1-154048;JP-A-1-155338; JP-A-1-155339; JP-A-1-188852; Y. Tani et at: Proc. SPIE,1086, 22 (1989), etc.). These dissolution-inhibiting type resistmaterials, however, are all low in sensitivity and unusable forapplications involving use of deep ultraviolet light or KrF excimerlaser light where a high-sensitivity resist material is required.Recently, as means for reducing the amount of energy required forexposure (means for elevating sensitivity), use of a chemicallyamplified resist material with an exposure-generated acid applied asmedium has been proposed [H. Ito et al: Polym. Eng. Sci., 23, 1012(1983)], and many reports on this type of resist material have been madepublic (U.S. Pat. No. 4,491,628 (1985) to H. Ito et al; JP-A-2-27660;U.S. Pat. No. 4,603,101 (1986) to J. C. Crivello et al; JP-A-62-115440;W. R. Brunsvolt et al: Proc. SPIE, 1086, 357 (1989); T. X. Neenan et al:Proc. SPIE, 1086, 2 (1989); R. G. Tarascon et al: SPE RegionalConference Technical Papers, Ellenville, N.Y., p. 11, 1988;JP-A-2-25850; Y. Jian et al: Polym. Mater. Sci. & Eng., 66, 41 (1992),etc.). These known chemically amplified resist materials, however, alsohave varied problems in practical use depending on the type of thepolymer used. For example, in case of using phenol ether type polymerssuch as poly(p-tert-butoxycarbonyloxystyrene),poly(p-tert-butoxystyrene),poly(p-tert-butoxycarbonyloxy-α-methylstyrene),poly(p-tert-butoxy-α-methylstyrene), poly(tert-butylp-isopropenylphenoxy-acetate),poly(p-tert-butoxycarbonyloxystyrene/sulfone),poly(p-tetrahydropyranyloxystyrene), poly {p-(1-methoxyethoxy)styrene},poly {p-(1-phenoxyethoxy)styrene} or the like, the produced resistmaterial tends to cause film separation during development due to pooradhesion to the substrate, and such resist material also proves poor inheat resistance, making it unable to obtain a good pattern. In case ofusing a carboxylic acid type polymer such as poly(tert-butylp-vinylbenzoate) or poly(tetrahydropyranyl p-vinylbenzoate), theproduced resist material is found unsatisfactory in permeability tolight with a wavelength around 248.4 nm due to the presence of benzoylgroup and therefore has poor resolution. In the case of poly(tert-butylmethacrylate), there are the problems of unsatisfactory heat resistance,poor dry etch resistance.

Resist materials using silicon-containing polymers have also beendisclosed (JP-B-3-44290, etc.), but use of such silicon-containingpolymers, for instance, poly(p-trimethylsilyloxystyrene) orpoly(p-tert-butyldimethylsilyloxystyrene), is encounted with theproblems such as low sensitivity and impossibility to perfectly removethe resist material by ashing as it contains silicon. Thus, these resistmaterials are hardly capable of practical use.

More recently, as the chemically amplified resist materials freed of thedefects mentioned above, there have been reported a resist materialusing poly(p-tert-butoxycarbonyloxystyrene/p-hydroxystyrene)(JP-A-2-209977; JP-A-3-206458), a resist material usingpoly(p-tetrahydropyranyloxystyrene/p-hydroxystyrene) (JP-A-2-19847;JP-A-2-161436; JP-A-3-83063) and a resist material usingpoly(p-tert-butoxystyrene/p-hydroxystyrene) [JP-A-2-62544; JP-A-4-211258(U.S. Pat. No. 5,350,660)]. The resist materials using these polymers,however, involve the problem of delay time (the problem of change ofpattern size or deformation during the period from resist coating tillexposure or from exposure till heat treatment (PEB)) which is hotlydiscussed recently in practical application of resist materials.

Further, resist materials using the polymers having an acetal group orketal group introduced as protective group have also been reported(JP-A-2-19847; JP-A-2-161436; JP-A-4-219757; JP-A-5-281745;JP-A-5-249682). However, the resist materials using these polymers, forexample, poly(p-1-ethoxyethoxystyrene/p-hydroxystyrene),poly(p-1-methoxyethoxystyrene/p-hydroxystyrene),poly(p-1-methoxy-1-methylethoxystyrene/p-hydroxystyrene),poly(p-1-ethoxyethoxystyrene/p-hydroxystyrene/methyl methacrylate) andpoly(p-1-ethoxyethoxystyrene/p-hydroxystyrene/fumaronitrile) have theproblems of poor storage stability, great deterioration of pattern sizeand shape on defocuing and small focus margin, so that it is difficultto form resist patterns with consistent stability by using these resistmaterials. They also involve the problems of formation of scums(non-dissolved portion at the time of development) and poor masklinearity. JP-A-3-282550 discloses a resist material comprisingpoly(1-methoxy-1-methylethoxystyrene/p-hydroxystyrene) anddiphenyliodium salt, but this resist material has the problems of pooradhesiveness to the substrate and delay time in addition to the problemsmentioned above. Resist materials using the polymers according to thepresent invention, for example,poly(p-1-ethoxyethoxystyrene/p-hydroxystyrene/p-tert-butoxystyrene) havealso been reported (JP-A-6-194842). These resist materials, however, areall designed for use with electron rays, and if they are exposed toultraviolet light, such as KrF excimer laser light, there arise suchproblems as imperfect resolution of the bottom portion (footing) of thepattern and formation of scums and consequent transfer of such scums tothe pattern during etching.

As viewed above, the chemically amplified resist materials, althoughhigh in sensitivity as compared with the conventional resist materials,still have difficult problems such as poor heat resistance of polymersused therefor, imperfect adhesion to the substrate, insufficienttransmittance to light with a wavelength around 248.4 nm, unsatisfactoryresolving performance, change of pattern size or deterioration ofpattern shape with time, poor storage stability, insufficient focusmargin, unsatisfactory mask linearity, footing of the pattern andformation of scums, which discourage practical application of theseresist materials. Thus, the appearance of a practical high-sensitivityresist material freed of the above-said problems has been desired.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above circumstancesand it has for its object to provide a practical resist material whichhas high transmittance to ultraviolet light, especially deep ultravioletlight with a wavelength of 300 nm or less such as KrF excimer laserlight, has high sensitivity to exposure to these light sources orirradiation with electron beam or soft X-rays, has excellent heatresistance and adhesiveness to the substrate, has high resolution, won'tcause change of pattern size with time to allow formation of a patternwith high accuracy, has excellent storage stability, has a broad focusmargin and good mask linearity, and is capable of forming a pattern ofrectangular shape without causing footing of the pattern or formation ofscums, and a pattern forming process using such a resist material.

The present invention provides a resist material comprising:

(a) a polymer represented by the formula [1]: ##STR1## wherein R¹ is ahydrogen atom or a methyl group; R² and R³ are independently a hydrogenatom, a straight-chain, branched or cyclic alkyl group having 1-6 carbonatoms, a straight-chain or branched haloalkyl group having 1-6 carbonatoms or a phenyl group, provided that R² and R³ are not hydrogen atomat the same time, or R² and R³ may combine to form a methylene chainhaving 2-5 carbon atoms; R⁴ is a straight-chain, branched or cyclicalkyl group having 1-10 carbon atoms, a straight-chain, branched orcyclic haloalkyl group having 1-6 carbon atoms, an acetyl group or anaralkyl group; R⁵ is a hydrogen atom, a straight-chain, branched orcyclic alkyl group having 1-6 carbon atoms, a straight-chain, branchedor cyclic alkoxy group having 1-6 carbon atoms, a tetrahydropyranyloxygroup, a tetrahydrofuranyloxy group, a tert-butoxycarbonyloxy group, atert-butoxycarbonylmethoxy group or an acetyloxy group; and k, r and mare independently an integer of 1 or more, provided that0.10≦(k+m)/(k+r+m)≦0.90 and 0.01≦m/(k+r+m)≦0.25;

(b) at least one photosensitive compound capable of generating an acidupon exposure to light, selected from the group consisting of thephotosensitive compounds represented by the following formula [2], thephotosensitive compounds represented by the formula [3], thephotosensitive compounds represented by the formula [5], thephotosensitive compounds represented by the formula [6], thephotosensitive compounds represented by the formula [9] and thephotosensitive compounds represented by the formula [12]: ##STR2##wherein R⁶ and R⁷ are independently a straight-chain, branched or cyclicalkyl group having 1-10 carbon atoms; and Z is a sulfonyl group or acarbonyl group; ##STR3## wherein R⁸ is a hydrogen atom, a halogen atom,a straight-chain or branched alkyl group having 1-5 carbon atoms, astraight-chain or branched alkoxy group having 1-5 carbon atoms, or astraight-chain or branched haloalkyl group having 1-5 carbon atoms; andR⁹ is a straight-chain, branched or cyclic alkyl group having 1-10carbon atoms, a haloalkyl group having 1-10 carbon atoms, or a grouprepresented by the formula [4]: ##STR4## wherein R¹⁰ is a hydrogen atom,a halogen atom, a straight-chain or branched alkyl group having 1-5carbon atoms, a straight-chain or branched alkoxy group having 1-5carbon atoms, or a straight-chain or branched haloalkyl group having 1-5carbon atoms; and n is 0 or an integer of 1-3; ##STR5## wherein R¹¹ is ahydrogen atom, a halogen atom, a straight-chain or branched alkyl grouphaving 1-5 carbon atoms, an aralkyl group or a trifluoromethyl group;R¹² is a straight-chain, branched or cyclic alkyl group having 1-10carbon atoms, an aralkyl group, a straight-chain or branched alkoxygroup having 1-5 carbon atoms, a phenyl group or a tolyl group; ##STR6##wherein R¹³ is a group represented by the formula [7]: ##STR7## whereinR¹⁴, R¹⁵ and R¹⁶ are independently a hydrogen atom or a halogen atom;and p is 0 or an integer of 1-3, or a group represented by the formula[8]: ##STR8## wherein R¹⁷, R¹⁸, R¹⁹, R²⁰ and R²¹ are independently ahydrogen atom, a halogen atom, a straight-chain or branched alkyl grouphaving 1-5 carbon atoms, a straight-chain or branched alkoxy grouphaving 1-5 carbon atoms, a trifluoromethyl group, a hydroxyl group, atrifluoromethoxy group or a nitro group; ##STR9## wherein R¹³ is asdefined above; R²² is a hydrogen atom, a hydroxyl group or a grouprepresented by the formula [10]:

    R.sup.13 SO.sub.2 O--                                      [10]

wherein R¹³ is as defined above; and R²³ is a straight-chain or branchedalkyl group having 1-5 carbon atoms or a group represented by theformula [11]: ##STR10## wherein R²⁴ and R³⁰ are independently a hydrogenatom, a halogen atom, a straight-chain or branched alkyl group having1-5 carbon atoms, a straight-chain or branched alkoxy group having 1-5carbon atoms, or a group of the formula [10]; ##STR11## wherein R²⁵ is astraight-chain or branched alkyl group having 1-4 carbon atoms, a phenylgroup, a substituted phenyl group or an aralkyl group; R²⁶ is a hydrogenatom, a halogen atom or a straight-chain, branched or cyclic alkyl grouphaving 1-6 carbon atoms; R²⁷ is a straight-chain or branchedperfluoroalkyl group having 1-8 carbon atoms, a straight-chain, branchedor cyclic alkyl group having 1-8 carbon atoms, a 1-naphthyl group, a2-naphthyl group, a 10-camphor group, a phenyl group, a tolyl group, a2,5-dichlorophenyl group, a 1,3,4-trichlorophenyl group or atrifluoromethylphenyl group; and

(c) a solvent capable of dissolving the above substances.

The present invention also provides a pattern forming process comprisingthe steps of coating the resist material described above on a substrate;heating and exposing the coating film to light of 300 nm or less througha mask; heating the exposed coating film if necessary; and developingthe film with a developing solution.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1A-1C are the sectional views illustrating the process for forminga positive pattern using a resist material according to the presentinvention.

FIG. 2 is a favorable mask linearity (mask fidelity) curve of the resistmaterial obtained in Example 2.

FIG. 3 is a good pattern having no tail or scum at its bottom portion,obtained in Example 17.

FIG. 4 is a sectional view showing T-shaping of the coating filmobserved when a positive pattern was formed by using the resist materialof Comparative Example 1.

FIG. 5 is a sectional view illustrating failure in forming a pattern asobserved when it was tried to form a positive pattern by using theresist materials of Comparative Examples 2-8.

FIG. 6 shows a pattern of improper shape obtained in Comparative Example15 where tails were seen at the bottom portion of the pattern.

FIG. 7 is an unfavorable mask linearity (mask fidelity) curve of theresist material obtained in Comparative Example 15.

FIG. 8 shows a defective pattern having scums at its bottom portion,obtained in Comparative Example 17.

FIG. 9 shows a pattern of improper shape observed in pattern formingaccording to Comparative Example 18.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The resist material according to the present invention comprises:

(a) a polymer represented by the formula [1]: ##STR12## wherein R¹ is ahydrogen atom or a methyl group; R² and R³ are independently a hydrogenatom, a straight-chain, branched or cyclic alkyl group having 1-6 carbonatoms, a straight-chain or branched haloalkyl group having 1-6 carbonatoms, or a phenyl group, provided that R² and R³ are not hydrogen atomat the same time, or R² and R³ may combine to form a methylene chainhaving 2-5 carbon atoms; R⁴ is a straight-chain, branched or cyclicalkyl group having 1-10 carbon atoms, a straight-chain, branched orcyclic haloalkyl group having 1-6 carbon atoms, an acetyl group or anaralkyl group; R⁵ is a hydrogen atom, a halogen atom, a straight-chain,branched or cyclic alkyl group having 1-6 carbon atoms, astraight-chain, branched or cyclic alkoxy group having 1-6 carbon atoms,a tetrahydroxypyranyloxy group, a tetrahydrofuranyloxy group, atert-butoxycarbonyloxy group, a tert-butoxycarbonylmethoxy group or anacetyloxy group; and k, r and m are independently an integer of 1 ormore, provided that 0.10≦(k+m)/(k+r+m)≦0.90 and 0.01≦m/(k+r+m)≦0.25;

(b) at least one photosensitive compound capable of generating an acidupon exposure to light, selected from the group consisting of thephotosensitive compounds represented by the following formulae [2], [3],[5], [6], [9] and [12]: ##STR13## wherein R⁶ and R⁷ are independently astraight-chain, branched or cyclic alkyl group having 1-10 carbon atomsor a haloalkyl group having 1-10 carbon atoms; and Z is a sulfonyl groupor a carbonyl group; ##STR14## wherein R⁸ is a hydrogen atom, a halogenatom, a straight-chain or branched alkyl group having 1-5 carbon atoms,a straight-chain or branched alkoxy group having 1-5 carbon atoms or astraight-chain or branched haloalkyl group having 1-5 carbon atoms; andR⁹ is a straight-chain, branched or cyclic alkyl group having 1-10carbon atoms, a haloalkyl group having 1-10 carbon atoms or a grouprepresented by the formula [4]: ##STR15## wherein R¹⁰ is a hydrogenatom, a halogen atom, a straight-chain or branched alkyl group having1-5 carbon atoms, a straight-chain or branched alkoxy group having 1-5carbon atoms or a straight-chain or branched haloalkyl group having 1-5carbon atoms; and n is 0 or an integer of 1-3; ##STR16## wherein R¹¹ isa hydrogen atom, a halogen atom, a straight-chain or branched alkylgroup having 1-5 carbon atoms, an aralkyl group or a trifluoromethylgroup; and R¹² is a straight-chain, branched or cyclic alkyl grouphaving 1-10 carbon atoms, an aralkyl group, a straight-chain or branchedalkoxy group having 1-5 carbon atoms, a phenyl group or a tolyl group;##STR17## wherein R¹³ is a group represented by the formula [7]:##STR18## wherein R¹⁴, R¹⁵ and R¹⁶ are independently a hydrogen atom ora halogen atom; and p is 0 or an integer of 1-3, or a group representedby the formula [8]: ##STR19## wherein R¹⁷, R¹⁸, R¹⁹, R²⁰ and R²¹ areindependently a hydrogen atom, a halogen atomd, a straight-chain orbranched alkyl group having 1-5 carbon atoms, a straight-chain orbranched alkoxy group having 1-5 carbon atoms, a trifluoromethyl group,a hydroxyl group, a trifluoromethoxy group or a nitro group; ##STR20##wherein R¹³ is as defined above, R²² is a hydrogen atom, a hydroxylgroup or a group represented by the formula [10]:

    R.sup.13 SO.sub.2 O--                                      [10]

wherein R¹³ is as defined above; and R²³ is a straight-chain or branchedalkyl group having 1-5 carbon atoms or a group represented by theformula [11]: ##STR21## wherein R²⁴ and R²⁵ are independently a hydrogenatom, a halogen atom, a straight-chain or branched alkyl group having1-5 carbon atoms, a straight-chain or branched alkoxy group having 1-5carbon atoms or a group of the formula [10]; ##STR22## wherein R²⁵ is astraight-chain or branched alkyl group having 1-4 carbon atoms, a phenylgroup, a substituted phenyl group or an aralkyl group; R²⁶ is a hydrogenatom, a halogen atom or a straight-chain, branched or cyclic alkyl grouphaving 1-6 carbon atoms; and R²⁷ is a straight-chain or branchedperfluoroalkyl group having 1-8 carbon atoms, a straight-chain, branchedor cyclic alkyl group having 1-8 carbon atoms, a 1-naphthyl group, a2-naphthyl group, a 10-camphor group, a phenyl group, a tolyl group, a2,5-dichlorophenyl group, a 1,3,4-trichlorophenyl group or atrifluoromethylphenyl group; and

(c) a solvent capable of dissolving the above substances.

The C₁₋₆ alkyl groups represented by R², R³ and R⁵ in the formula [1]and the alkyl group in the C₁₋₆ haloalkyl groups represented by R², R³and R⁴ include methyl, ethyl, propyl, butyl, pentyl and hexyl (all ofthese groups may be straight-chain, branched or cyclic). The C₁₋₁₀ alkylgroup represented by R⁴ includes methyl, ethyl, propyl, butyl, pentyl,hexyl, heptyl, octyl, nonyl and decyl (all of these groups may bestraight-chain, branched or cyclic). The C₁₋₆ alkoxy group representedby R⁵ includes methoxy, ethoxy, propoxy, butoxy, pentyloxy and hexyloxy(all of these groups may be straight-chain, branched or cyclic). One ormore halogen atoms in the C₁₋₆ haloalkyl groups represented by R², R³and R⁴ and the halogen atom represented by R⁵ include chlorine, bromine,fluorine and iodine. The aralkyl group represented by R⁴ includesbenzyl, phenetyl, phenylpropyl, methylbenzyl, methylphenetyl andethylbenzyl.

The C₁₋₁₀ alkyl groups and the alkyl group in the C₁₋₁₀ haloalkyl groupsrepresented by R⁶ and R⁷ in the formula [2] include methyl, ethyl,propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl and decyl (all ofthese groups may be straight-chain, branched or cyclic).

The C₁₋₅ alkyl groups and the alkyl group in the C₁₋₅ haloalkyl groupsrepresented by R⁸ in the formula [3] include methyl, ethyl, propyl,butyl and pentyl (which may be straight-chain, branched or cyclic). TheC₁₋₅ alkoxy groups represented by R⁸ include methoxy, ethoxy, propoxy,butoxy and pentyloxy (which may be straight-chain or branched). TheC₁₋₁₀ alkyl groups and the alkyl group in the C₁₋₁₀ haloalkyl groupsrepresented by R⁹ include methyl, ethyl, propyl, butyl, pentyl, hexyl,heptyl, octyl, nonyl and decyl (which may be straight-chain, branched orcyclic). The halogen atom represented by R⁸, one or more halogen atomsin the C₁₋₅ haloalkyl groups represented by R⁸ and one or more halogenatoms in the C₁₋₁₀ haloalkyl groups represented by R⁹ include chlorine,bromine, fluorine and iodine.

The C₁₋₅ alkyl group and the alkyl group in the C₁₋₅ haloalkyl groupsrepresented by R¹⁰ in the formula [4] include methyl, ethyl, propyl,butyl and pentyl (which may be straight-chain or branched). The C₁₋₅alkoxy group represented by R¹⁰ includes methoxy, ethoxy, propoxy,butoxy and pentyloxy (which may be straight-chain or branched).

The halogen atom and one or more halogen atoms in the C₁₋₅ haloalkylgroup represented by R¹⁰ include chlorine, bromine, fluorine and iodine.

The C₁₋₅ alkyl groups represented by R¹¹ in the formula [5] includemethyl, ethyl, propyl, butyl and pentyl (which may be straight-chain orbranched). The C₁₋₁₀ alkyl groups represented by R¹² include methyl,ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl and decyl(which may be straight-chain, branched or cyclic). The C₁₋₅ alkoxygroups represented by R¹² include methoxy, ethoxy, propoxy, butoxy andpentyloxy (which may be straight-chain or branched). The aralkyl groupsrepresented by R¹² include benzyl, phenetyl, phenylpropyl, methylbenzyl,methylphenetyl and ethylbenzyl. The halogen atoms represented by R¹¹include chlorine, bromine, fluorine and iodine.

The halogen atoms represented by R¹⁴, R¹⁵ and R¹⁶ in the formula [7]include chlorine, bromine, fluorine and iodine.

The C₁₋₅ alkyl groups represented by R¹⁷, R¹⁸, R¹⁹, R²⁰ and R²¹ in theformula [8] include methyl, ethyl, propyl, butyl and pentyl (which maybe straight-chain or branched). The C₁₋₅ alkoxy groups represented byR¹⁷ -R²¹ include methoxy, ethoxy, propoxy, butoxy and pentyloxy (whichmay be straight-chain or branched). The halogen atoms represented by R¹⁷-R²¹ include chlorine, bromine, fluorine and iodine.

The C₁₋₅ alkyl groups represented by R²³ in the formula [9] includemethyl, ethyl, propyl, butyl and pentyl (which may be straight-chain orbranched).

The C₁₋₅ alkyl groups represented by R²⁴ in the formula [11] includemethyl, ethyl, propyl, butyl and pentyl (which may be straight-chain orbranched). The C₁₋₅ alkoxy groups represented by R²⁴ include methoxy,ethoxy, propoxy, butoxy and pentyloxy (which may be straight-chain orbranched). The halogen atoms represented by R²⁴ include chlorine,bromine, fluorine and iodine.

The C₁₋₄ alkyl groups represented by R²⁵ in the formula [12] includemethyl, ethyl, propyl and butyl (which may be straight-chain orbranched). The C₁₋₆ alkyl groups represented by R²⁶ include methyl,ethyl, propyl, butyl, pentyl and hexyl (which may be straight-chain,branched or cyclic). The substituted phenyl groups represented by R²⁵include tolyl, ethylphenyl, tert-butylphenyl and chlorophenyl (thesubstitution position may be o-, m- or p-position). The aralkyl groupsrepresented by R²⁵ include benzyl and phenetyl. The halogen atomsrepresented by R²⁶ include chlorine, bromine, fluorine and iodine. TheC₁₋₈ perfluoroalkyl groups represented by R²⁷ include trifluoromethyl,pentafluoroethyl, perfluoropropyl, perfluorobutyl, perfluoropentyl,perfluorohexyl, perfluoroheptyl andperfluorooctyl (which may bestraight-chain or branched). The C₁₋₈ alkyl groups represented by R²⁷include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl and octyl(which may be straight-chain or branched).

Preferred examples of the polymers represented by the formula [1], whichcan be used for the resist material according to the present invention,are those of the formula [1] in which R¹ is hydrogen atom, R² ishydrogen atom or straight-chain or branched alkyl group having 1-6carbon atoms, R³ is straight-chain or branhced alkyl group having 1-6carbon atoms, R⁴ is straight-chain or branched alkyl group having 1-10carbon atoms, and R⁵ is hydrogen atom, straight-chain, branched orcyclic alkyl group having 1-6 carbon atoms, a straight-chain, branchedor cyclic alkoxy group having 1-6 carbon atoms, a tert-butoxycarbonyloxygroup, a tert-butoxycarbonylmethoxy group, a tetra-hydropyranyloxy groupor an acetyloxy group. More preferred examples of said polymers arethose of the formula [1] in which R¹ is a hydrogen atom, R² is ahydrogen atom or a methyl group, R³ is a methyl group or ethyl group, R⁴is a straight-chain or branched alkyl group having 1-4 carbon atoms, andR⁵ is a hydrogen atom, a straight-chain or branched alkyl group having1-4 carbon atoms, a straight-chain or branched alkoxy group having 1-4carbon atoms, a tert-butoxycarbonyloxy group, atert-butoxycarbonylmethoxy group or an acetyloxy group.

The polymers of the formula [1] according to the present invention arespecifically characterized by comprising a monomer unit having afunctional group which can be easily eliminated with a trace amount ofan acid and represented by the formula [13]: ##STR23## wherein R², R³and R⁴ are as defined above, such as alkoxyalkoxyl group,haloalkoxyalkoxyl group or aralkyloxyalkoxyl group, or a monomer unitrepresented by the formula [14]: ##STR24## wherein R¹, R², R³ and R⁴ areas defined above, and a monomer unit capable of controlling thedeveloping speed at the exposed portion to better mask linearity whilerepressing the influence of undesirable approximation, or a monomer unitrepresented by the formula [15]: ##STR25## wherein R¹ and R⁵ are asdefined above. Especially the functional groups represented by theformula [13] are highly prone to elimination by the action of an acid ascompared with the conventional functional groups such astert-butoxycarbonyloxy group, tert-butoxy group, tetrahydropyranyloxygroup and tert-butoxycarbonylmethyloxy group, and therefore haveadvantages in that they contribute to the improvement of resolvingperformance and maintenance of pattern size and shape. The monomer unitof the formula [15] is very effective for improving focus margin andbettering mask linearity, which effect can not be expected from themonomer unit of the formula [14] having a functional group of theformula [13]. This monomer unit is also conducive to the improvement ofheat resistance of the polymer.

The monomer unit represented by the formula [14] comprises specificallysuch monomers as p- or m-hydroxystyrene derivatives, p- orm-hydroxy-α-methylstyrene derivatives, etc. Examples of these monomersare p- or m-1-methoxy-1-methylethoxystyrene, p- orm-1-benzyloxy-1-methylethoxystyrene, P- or m-1-ethoxyethoxystyrene, p-or m-1-methoxyethoxystyrene, p- or m-1-n-butoxyethoxystyrene, p- orm-1-isobutoxyethoxystyrene, p- orm-1-(1,1-dimethylethoxy)-1-methylethoxystyrene, p- orm-1-(1,1-dimethylethoxy)ethoxystyrene, p- orm-1-(2-chloroethoxy)ethoxystyrene, p- orm-1-(2-ethylhexyloxy)ethoxystyrene, p- orm-1-ethoxy-1-methylethoxystyrene, p- or m-1-n-propoxyethoxystyrene, p-or m-1-methyl-1-n-propoxyethoxystyrene, p- or m-1-ethoxypropoxystyrene,p- or m-1-methoxybutoxystyrene, p- or m-1-methoxycyclohexyloxystyrene,p- or m-1-acetyloxy-1-methylethoxystyrene, and p- orm-hydroxy-α-methylstyrene derivatives having the same protective groupsas the above-mentioned p- or m-hydroxystyrene derivatives.

The polymers according to the present invention are the copolymerscomprising a monomer unit of the formula [14] shown above, a monomerunit of the formula [15] shown above and a monomer unit represented bythe formula [16]: ##STR26## wherein R¹ is as defined above, which hasthe function of bettering heat resistance of the polymer and itsadhesiveness to the substrate. The monomer units of the formula [15]include styrene, p-chlorostyrene, o-, m- or p-methylstyrene, o-, m- orp-methoxystyrene, p-m-butylstyrene, p-ethoxystyrene, m- orp-tert-butoxystyrene, m- or p-tetrahydropyranyloxystyrene, m- orp-tetrahydrofuranyloxystyrene, m- or p-tert-butoxycarbonyloxystyrene,tert-butyl m- or p- vinylphenoxyacetate, m- or p-acetyloxystyrene, andα-methylstyrene derivatives having the same substituents as theabove-mentioned styrene derivatives.

The monomer unit of the formula [16] comprises the monomers havingphenolic hydroxyl groups. Typical examples of such monomers are p- orm-vinylphenol and p- or m-hydroxy-α-methylstyrene.

In the polymers of the formula [1] according to the present invention,the ratios of the monomer unit of the formula [14], the monomer unit ofthe formula [15] and the monomer unit of the formula [16] are asdescribed below. The ratio of the sum of the monomer unit [14] and themonomer unit [15] to the whole amount of the polymer is preferably10-90% by mole, more preferably 20-70% by mole for obtaining the maximalimprovement of heat resistance of the polymer, its adhesiveness to thesubstrate and mask linearity.

The ratio of the monomer unit [15] to the whole amount of the polymer ispreferably 1-25% by mole, more preferably 2-20% by mole for obtaining aneffect of bettering mask linearity and inhibiting drop of resolution.

Of the polymers of the formula [1] according to the present invention,those of the formula [1] wherein R¹ is hydrogen atom, R² is hydrogenatom or methyl group, R³ is methyl group or ethyl group, R⁴ isstraight-chain or branched alkyl group having 1-10 carbon atoms and R⁵is hydrogen atom, straight-chain or branched alkyl group having 1-4carbon atoms, straight-chain or branched alkoxy group having 1-4 carbonatoms or acetyl group, are preferred since the starting monomers areeasily available as commercial products and the number of the steps forthe synthesis is small. These polymers are also advantageous in terms ofcost and can be easily applied to industrial uses.

Listed below are examples of the polymers according to the presentinvention:

poly[p-(1-methoxy-1-methylethoxy)styrene/p-hydroxystyrene/styrene],

poly[p-(1-methoxy-1-methylethoxy)styrene/p-hydroxystyrene/p-chlorostyrene],

poly[p-(1-methoxy-1-methylethoxy)styrene/p-hydroxystyrene/p-methylstyrene],

poly[p-(1-methoxy-1-methylethoxy)styrene/p-hydroxystyrene/p-methoxystyrene]

poly[p-(1-methoxy-1-methylethoxy)styrene/p-hydroxystyrene/p-tert-butoxystyrene],

poly[p-(1-methoxy-1-methylethoxy)styrene/p-hydroxystyrene/p-acetyloxystyrene],

poly[p-(1-benzyloxy-1-methylethoxy)styrene/p-hydroxystyrene/styrene],

poly[p-(1-benzyloxy-1-methylethoxy)styrene/p-hydroxystyrene/p-chlorostyrene],

poly[p-(1-benzyloxy-1-methylethoxy)styrene/p-hydroxystyrene/p-methylstyrene],

poly[p-(1-benzyloxy-1-methylethoxy)styrene/p-hydroxystyrene/p-ethoxystyrene],

poly[p-(1-benzyloxy-1-methylethoxy)styrene/p-hydroxystyrene/p-tert-butoxystyrene],

poly(p-1-ethoxystyrene/p-hydroxystyrene/styrene),

poly(p-1-ethoxyethoxystyrene/p-hydroxystyrene/p-chlorostyrene),

poly(p-1-ethoxyethoxystyrene/p-hydroxystyrene/p-methylstyrene),

poly(p-1-ethoxyethoxystyrene/p-hydroxystyrene/m-methylstyrene),

poly(p-1-ethoxyethoxystyrene/p-hydroxystyrene/p-methoxystyrene),

poly(p-1-ethoxyethoxystyrene/p-hydroxystyrene/p-ethoxystyrene),

poly(p-1-ethoxyethoxystyrene/p-hydroxystyrene/p-tert-butoxystyrene),

poly(p-1-ethoxyethoxystyrene/p-hydroxystyrene/p-acetyloxystyrene),

poly(p-1-methoxyethoxystyrene/p-hydroxystyrene/styrene),

poly(p-1-methoxyethoxystyrene/p-hydroxystyrene/p-methylstyrene),

poly(p-1-methoxyethoxystyrene/p-hydroxystyrene/m-methylstyrene),

poly(p-1-methoxyethoxystyrene/p-hydroxystyrene/p-chlorostyrene),

poly(p-1-methoxyethoxystyrene/p-hydroxystyrene/p-methoxystyrene),

poly(p-1-methoxyethoxystyrene/p-hydroxystyrene/p-ethoxystyrene),

poly(p-1-methoxyethoxystyrene/p-hydroxystyrene/p-tert-butoxystyrene),

poly(p-1-methoxyethoxystyrene/p-hydroxystyrene/p-acetyloxystyrene),

poly(p-1-n-butoxyethoxystyrene/p-hydroxystyrene/p-n-butylstyrene),

poly(p-1-isobutoxyethoxystyrene/p-hydroxystyrene/o-methoxystyrene),

poly{p-[(1,1-dimethylethoxy)-1-methylethoxy]styrene/p-hydroxystyrene/m-methoxystyrene]},

poly[p-(1,1-dimethylethoxy)-1-methylethoxystyrene/p-hydroxystyrene/o-methylstyrene),

poly[m-1-(2-chloroethoxy)ethoxystyrene/m-hydroxystyrene/styrene],

poly[m-1-(2-ethylhexyloxy)ethoxystyrene/m-hydroxystyrene/m-methylstyrene],

poly[p-(1-methoxy-1-methylethoxy)-α-methylstyrene/p-hydroxy-α-methylstyrene/styrene],

poly[p-(1-ethoxy-1-methylethoxy)styrene/p-hydroxystyrene/p-methylstyrene],

poly(p-1-n-propoxyethoxystyrene/p-hydroxystyrene/p-methoxystyrene),

poly[p-(1-methyl-1-n-propoxyethoxy)styrene/p-hydroxystyrene/p-methylstyrene],

poly(m-1-ethoxypropoxystyrene/m-hydroxystyrene/m-ter-tbutoxystyrene),

poly(p-1-acetyloxy-1-methylethoxystyrene/p-hydroxystyrene/p-tert-butoxystyrene),

poly(m-1-ethoxypropoxystyrene/m-hydroxystyrene/p-methylstyrene),

poly[m-(1-methoxy-1-methylethoxy)styrene/m-hydroxystyrene/m-tert-butoxystyrene],

poly(p-1 -methoxychlorohexyloxystyrene/p-hydroxystyrene),

poly[p-(1-ethoxyethoxy)styrene/p-hydroxystyrene/p-tetrahydrofuranyloxystyrene],

poly[p-(1-ethoxyethoxy)styrene/p-hydroxystyrene/p-tetrahydropyranyloxystyrene,

poly[p-(1-methoxyethoxy)styrene/p-hydroxystyrene/p-tetrahydropyranyloxystyrene],

poly[p-(1-ethoxyethoxy)styrene/p-hydroxystyrene/p-tert-butoxycarbonyloxystyrene],

poly[p-(1-methoxyethoxy)styrene/p-hydroxystyrene/p-tert-butoxycarbonyloxystyrene],

poly[p-(1-methoxy-1-methylethoxy)styrene/p-hydroxystyrene/p-tert-butoxycarbonyloxystyrene],

poly[p-(1-ethoxyethoxy)styrene/p-hydroxystyrene/tert-butylp-vinylphenoxyacetate],

poly[p-(1-methoxyethoxy)styrene/p-hydroxystyrene/tert-butylp-vinylphenoxyacetate],

poly[m-(1-ethoxyethoxy)styrene/m-hydroxystyrene/m-tert-butoxycarbonyloxystyrene],

poly(m-1-ethoxyethoxystyrene/m-hydroxystyrene/m-tert-butoxystyrene],

poly(m-1-methoxyethoxystyrene/m-hydroxystyrene/m-tert-butoxystyrene),and

poly(p-1-methoxybutoxystyrene/p-hydroxystyrened/styrene).

The polymers according to the present invention can be easily producedfrom the following six processes (a)-(f).

(a) Process 1

A monomer represented by the formula [17]: ##STR27## wherein R¹ is asdefined above, and an appropriate amount of a monomer represented by theformula [18]: ##STR28## wherein R¹ is as defined above and R²⁸ is ahydrogen atom, a halogen atom, a straight-chain, branched or cyclicalkyl group having 1-6 carbon atoms or a straight-chain or branchedalkoxy group having 1-3 carbon atoms, are polymerized in the presence ofa radical polymerization initiator [for example, an azo typepolymerization initiator such as 2,2'-azobisisobutyronitrile,2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(methyl2-methylpropionate), 2,2'-azobis(ethyl 2-methylpropionate) or2,2'-azobis(methyl 2-methylbutyrate), or a peroxide type polymerizationinitiator such as benzoyl peroxide or lauroyl peroxide] in an organicsolvent such as toluene, 1,4-dioxane, 1,2-dimethoxyethane,tetrahydrofuran, iso-propanol, 2-methoxypropanol, 1,3-dioxolane, ethylacetate or methyl ethyl ketone, in a nitrogen or argon gas stream at50°-110° C. for 1-10 hours. As the polymerization catalyst, anon-nitrile type catalyst such as 2,2'-azobis(methyl2-methylpropionate), 2,2'-azobis(ethyl 2-methylpropionate) or2,2'-azobis(methyl 2-methylbutyrate) is preferably used as this type ofcatalyst is suited for obtaining a low-molecular weight polymer becauseof high solubility and also advantageous in terms of safety andvirulence. It is also possible to carry out the reaction at an ultra-lowtemperature in the presence of a suitable catalyst such as butyl lithiumto perform anionic polymerization. The reaction is followed by pertinentafter-treatments according to a conventional method to isolate acopolymer represented by the formula [19]: ##STR29## wherein R¹, R²⁸ andm are as defined above, and q is an integer of 1 or more, provided that0.75≦q/q+m≦0.99. This copolymer is reacted with a proper acid [forexample, a Lewis acid such as sulfuric acid, phosphoric acid,hydrochloric acid or hydrobromic acid or an organic acid such asp-toluenesulfonic acid, malonic acid or oxalic acid] in an organicsolvent such as tetrahydrofuran, acetone, methanol, ethanol,iso-propanol, n-propanol, n-butanol, sec-butanol, tert-butanol,1,4-dioxane or 1,3-dioxolane, at 30°-110° C. for 1-20 hours to perfectlyeliminate tert-butyl groups which are functional groups. The reactionproduct is subjected to appropriate after-treatments according to aconventional method to isolate a hydroxystyrene copolymer represented bythe formula [20]: ##STR30## wherein R¹, R²⁸, q and m are as definedabove. This copolymer is further reacted with an adequate amount of avinyl ether or isopropenyl ether compound represented by the formula[21]: ##STR31## wherein R³ and R⁴ are as defined above, in an organicsolvent such as tetrahydrofuran, acetone, methyl ethyl ketone,1,4-dioxane, 1,3-dioxolane, methyl chloride, 1,2-dimethoxyethane, ethylether or ethyl acetate in the presence of a suitable catalyst such assulfuric acid, hydrochloric acid, phosphorus oxychloride,p-toluenesulfonic acid, chlorosulfonic acid pyridine salt, sulfuric acidpyridine salt or p-toluenesulfonic acid pyridine salt at 10°-100° C. for1-30 hours to chemically introduce the functional group of the formula[13] at a proper rate, followed by adequate after-treatments accordingto a conventional method to isolate the objective polymer.

(b) Process 2

A monomer of the formula [17] is polymerized in the same manner asdescribed in the Process 1, followed by after-treatments according to aconventional method to isolate a homopolymer represented by the formula[22]: ##STR32## wherein x=q+m, and R¹ is as defined above. Thishomopolymer is reacted with an appropriate acid [preferably a Lewis acidsuch as sulfuric acid, phosphoric acid, hydrochloric acid, hydrobromicacid, etc., or an organic acid such as p-toluenesulfonic acid, malonicacid, oxalic acid, etc.] in an organic solvent such as tetrahydrofuran,acetone, 1,4-dioxane, 1,3-dioxolane, methanol, ethanol, n-propanol,iso-propanol, n-butanol, sec-butanol, tert-butanol, etc., at 30°-100° C.for 1-10 hours to eliminate the functional tert-butyl groups at adesired rate. The reaction product is subjected to pertinentafter-treatments according to a conventional method to isolate ahydroxystyrene copolymer represented by the formula [23]: ##STR33##wherein R¹, m and q are as defined above. A functional group of theformula [13] is introduced into this copolymer in the same manner asdescribed in the Process 1 and then after-treatments are carried outaccording to a conventional method to isolate the objective polymer.

(c) Process 3

A monomer of the formula [24]: ##STR34## wherein R¹ is as defined above,and an adequate amount of a monomer of the formula [18] are polymerizedin the same manner as described in the Process 1, followed byafter-treatments according to a conventional method to isolate acopolymer represented by the formula [25]: ##STR35## wherein R¹, R²⁸, mand q are as defined above. This copolymer is further reacted in asolvent such as tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, ethylacetate, methanol, ethanol, n-propanol, iso-propanol, n-butanol,sec-butanol, tert-butanol or water, if possible in a nitrogen gasstream, in the presence of an appropriate base [preferably sodiumhydroxide, potassium hydroxide, ammonia water, hydroxylamine,tetramethylammonium hydroxide solution or the like] or an appropriateacid [preferably sulfuric acid, hydrochloric acid, hydrobromic acid,p-toluenesulfonic acid or the like] at 10°-120° C. for 0.5-20 hours toperfectly eliminate the functional acetyl groups. The reaction productis subjected to after-treatments according to a conventional method toisolate a hydroxystyrene copolymer represented by the formula [26]:##STR36## wherein R¹, R²⁸, m and q are as defined above. A functionalgroup of the formula [13] is introduced into this copolymer in the samemanner as described in the Process 1, followed by after-treatmentsaccording to a conventional method to isolate the objective polymer.

(d) Process 4

A monomer of the formula [24] is polymerized in the same manner asdescribed in the Process 1, followed by after-treatments according to aconventional method to isolate a homopolymer represented by the formula[27]: ##STR37## wherein R¹ and x are as defined above. This homopolymeris reacted in a solvent such as tetrahydrofuran, 1,4-dioxane,1,3-dioxolane, ethyl acetate, methanol, ethanol,n-propanol,iso-propanol, n-butanol, sec-butanol, tert-butanol or water,if possible in a nitrogen gas stream, in the presence of an appropriatebase [preferably sodium hydroxide, potassium hydroxide, ammonia water,hydroxylamine, tetramethylammonium hydroxide solution or the like] or anappropriate acid [preferably sulfuric acid, hydrochloric acid,phosphoric acid, hydrobromic acid, p-toluenesulfonic acid or the like]at 10°-100° C. for 0.5-10 hours to eliminate the functional acetylgroups at a desired rate. The reaction product is subjected toafter-treatments according to a conventional method to isolate ahydroxystyrene copolymer represented by the formula [28]: ##STR38##wherein R¹, q and m are as defined above. Into this copolymer isintroduced a functional group of the formula [13] in the same manner asdescribed in the Process 1 and after-treatments are conducted accordingto a conventional method to isolate the objective polymer.

(e) Process 5

A monomer of the formula [17] and an appropriate amount of a monomer ofthe formula [24] are polymerized in the same manner as described in theProcess 1, followed by after-treatments according to a conventionalmethod to isolate a copolymer represented by the following formula [29]:##STR39## wherein R¹, q and m are as defined above, or a copolymerrepresented by the following formula [30]: ##STR40## wherein R¹, q and mare as defined above. This copolymer is reacted in a solvent such astetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, ethyl acetate, methanol,ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, tert-butanolor water, if possible in a nitrogen gas stream, in the presence of anappropriate base [preferably sodium hydroxide, potassium hydroxide,ammonia water, hydroxylamine, tetramethylammonium hydroxide solution orthe like] at 10°-120° C. for 0.5-20 hours to perfectly eliminate thefunctional acetyl groups. Conventional after-treatments follow toisolate a hydroxystyrene copolymer of the formula [23] and thiscopolymer is treated in accordance with Process 2 to isolate theobjective polymer.

(f) Process 6

A homopolymer of the formula [22] obtained in Process 2 or a homopolymerof the formula [27] obtained in process 4 is reacted in a solvent suchas tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, ethyl acetate, methanol,ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, tert-butanolor water in the presence of an adequate acid [preferably sulfuric acid,hydrochloric acid, phosphoric acid, hydrobromic acid, p-toluenesulfonicacid, malonic acid, oxalic acid or the like] at 10°-70° C. for 0.5-10hours to perfectly eliminate the functional tert-butyl or acetyl groups.The reaction product is properly treated according to a conventionalmethod to isolate a hydroxystyrene polymer represented by the formula[31]: ##STR41## wherein R¹ and x are as defined above. This homopolymeris reacted with an appropriate amount of hydroxyl group protective agentsuch as di-tert-butyl dicarbonate, 2,3-dihydrofuran, 2,3-dihydropyran,tert-butyl monochloroacetate, acetyl chloride,acetic anhydride,isobutene, dimethylsulfuric acid, methyl iodide or the like in anorganic solvent such as tetrahydrofuran, 1,4-dioxane, ethyl acetate,methyl ethyl ketone, acetone, methylene chloride, 1,3-dioxolane,methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol,tert-butanol, methylene chloride or the like in the presence of apertinent base such as potassium hydroxide, sodium hydroxide, sodiumcarbonate, potassium carbonate, triethylamine, N-methyl-2-pyrrolidone,piperidine, tetramethylammonium hydroxide solution or the like or asuitable acid such as sulfuric acid, hydrochloric acid, phosphoric acid,phosphorus oxychloride, p-toluenesulfonic acid pyridine salt, sulfuricpyridine salt or the like at 10°-100° C. for 0.5-30 hours, and thereaction product is treated according to a conventional method to yielda copolymer represented by the formula [32]: ##STR42## wherein R²⁹ istert-butoxycarbonyloxy group, tetrahydrofuranyloxy group,tetrahydropyranyloxy group, tert-butoxycarbonylmethoxy group, acetylgroup, tert-butoxy group or methoxy group, and R¹ is as defined above.Into this copolymer is introduced a functional group of the formula [13]in the same manner as described in the Process 1, followed byafter-treatments according to a conventional method to isolate theobjective polymer.

The molecular weight of the polymers according to the present inventionis not specifically defined as far as the polymers are usable as resistmaterial, but preferably the weigth-average molecular weight of thepolymers as determined by GPC method using polystyrene as standard isusually about 1,000-100,000, more preferably about 3,000-50,000.

The photosensitive compounds capable of generating an acid upon epoxureto light (hereinafter referred to as "photoacid generator") used in thepresent invention include the compounds of the following formulae [2],[3], [5], [6], [9] and [12]: ##STR43## wherein R⁶, R⁷ and Z are asdefined above ##STR44## wherein R⁸ and R⁹ are as defined above.##STR45## wherein R¹¹ and R¹² are as defined above. ##STR46## whereinR¹³ is as defined above. ##STR47## wherein R¹³, R²² and R²³ are asdefined above ##STR48## wherein R²⁵, R²⁶ and R²⁷ are as defined above.

Listed below are preferred examples of the photoacid generators usablein the present invention.

Compounds of the Formula [2]

1-cyclohexylsulfonyl-1-(1,1-dimethylethylsulfonyl)diazomethane,bis(1,1-dimethylethylsulfonyl)diazomethane,bis(1-methylethylsulfonyl)diazomethane,bis(cyclohexylsulfonyl)diazomethane,1-cyclohexylsulfonyl-1-cyclohexylcarbonyldiazomethane,1-diazo-1-cyclohexylsulfonyl-3,3-dimethylbutan-2-one,1-diazo-1-methylsulfonyl-4-phenylbutan-2-one,1-diazo-1-(1,1-dimethylethylsulfonyl)-3,3-dimethyl-2-butanone,1-acetyl-1-(1-methylethylsulfonyl)diazomethane, etc.

Compounds of the Formula [3]

bis(p-toluenesulfonyl)diazomethane,methylsulfonyl-p-toluenesulfonyldiazomethane,1-diazo-1-(p-toluenesulfonyl)-3,3-dimethyl-2-butanone,bis(p-chlorobenzenesulfonyl)diazomethane,cyclohexylsulfonyl-p-toluenesulfonyldiazomethane, etc.

Compounds of the Formula [5]

1-p-toluenesulfonyl-1-cyclohexylcarbonyldiazomethane,1-diazo-1-(p-toluenesulfonyl)-3,3-dimethylbutan-2-one,1-diazo-1-benzenesulfonyl-3,3-dimethylbutan-2-one,1-diazo-1-(p-toluenesulfonyl)-3-methylbutan-2-one, etc.

Compounds of the Formula [6]

1,2,3-tris(trifluoromethanesulfonyloxy)benzene,1,2,3-tris(2,2,2-trifluoroethanesulfonyloxy)benzene,1,2,3-tris(2-chloroethanesulfonyloxy)benzene,1,2,3-tris(p-trifluoromethylbenzenesulfonyloxy)benzene,1,2,3-tris(p-nitrobenzenesulfonyloxy)benzene,1,2,3-tris(2,3,4,5,6-pentafluorobenzenesulfonyloxy)benzene,1,2,3-tris(p-fluorobenzenesulfonyloxy)benzene,1,2,3-tris(methanesulfonyloxy)benzene,1,2,4-tris(p-trifluoromethyloxybenzenesulfonyloxy)benzene,1,2,4-tris(2,2,2-trifluoroethanesulfonyloxy)benzene,1,2,4-tris(2-thienylsulfonyloxy)benzene,1,3,5-tris(methanesulfonyloxy)benzene,1,3,5-tris(trifluoromethanesulfonyloxy)benzene,1,3,5-tris(2,2,2-trifluoroethanesulfonyloxy)benzene,1,3,5-tris(p-nitrobenzenesulfonyloxy)benzene,1,3,5-tris(2,3,4,5,6-pentafluorobenzenesulfonyloxy)benzene,1,3,5-tris(p-fluorobenzenesulfonyloxy)benzene,1,3,5-tris(2-chloroethanesulfonyloxy)benzene, etc.

Compounds of the Formula [9]

2,3,4-tris(methanesulfonyloxy)benzophenone,2,3,4-tris(trifluoromethanesulfonyloxy)benzophenone,2,3,4-tris(2-chloroethanesulfonyloxy)benzophenone,2,3,4-tris(p-trifluoromethylbenzenesulfonyloxy)benzophenone,2,3,4-tris(p-nitrobenzenesulfonyloxy)benzophenone,2,3,4-tris(p-trifluoromethoxybenzenesulfonyloxy)benzophenone,2,3,4-tris(p-fluorobenzenesulfonyloxy)acetophenone,2,3,4-tris(2,3,4,5,6-pentafluorobenzenesulfonyloxy)acetophenone,2,3,4-tris(2-nitrobenzenesulfonyloxy)acetophenone,2,3,4-tris(2,5-dichlorobenzenesulfonyloxy)acetophenone,2,3,4-tris(2,3,4-trichlorobenzenesulfonyloxy)acetophenone,2,2',4,4'-tetra(methanesulfonyloxy)benzophenone,2,2',4,4'-tetra(2,2,2-trifluoroethanesulfonyloxy)benzophenone,2,2',4,4'-tetra(2-chloroethanesulfonyloxy)benzophenone,2,2',4,4'-tetra(2,5-dichlorobenzenesulfonyloxy)benzophenone,2,2',4,4'-tetra(2,4,6-trimethylbenzenesulfonyloxy)benzophenone,2,2',4,4'-tetra(m-trifluoromethylbenzenesulfonyloxy)benzophenone, etc.

Compounds of the Formula [12]

triphenylsulfonium trifluoromethanesulfonate, triphenylsulfoniumperfluorooctanesulfonate, diphenyl-p-tolylsulfoniumperfluorooctanesulfonate, tris(p-tolyl)sulfoniumperfluorooctanesulfonate, tris(p-chlorobenzene)sulfoniumtrifluoromethanesulfonate, tris(p-tolyl)sulfoniumtrifluoromethanesulfonate, trimethylsulfonium trifluoromethanesulfonate,dimethylphenylsulfonium trifluoromethanesulfonate,dimethyltolylsulfonium trifluoromethanesulfonate, dimethyltolylsulfoniumperfluorooctanesulfonate, triphenylsulfonium p-toluenesulfonate,triphenylsulfonium methanesulfonate, triphenylsulfoniumn-butanesulfonate, triphenylsulfonium n-octanesulfonate,triphenylsulfonium 1-naphthalenesulfonate, triphenylsulfonium2-naphthalenesulfonate, triphenylsulfonium 10-camphorsulfonate,triphenylsulfonium 2,5-dichlorobenzenesulfonate, diphenyltolylsulfonium1,3,4-trichlorobenzenesulfonate, dimethyltolylsulfoniump-toluenesulfonate,diphenyltolylsulfonium 2,5-dichloro-benzenesulfonate,etc.

The resist material of the present invention is characterized bycombined use of (a) a polymer of the formula [1] and (b) at least onephotoacid generator selected from the group consisting of thephotosensitive compounds of the formulae [2], [3], [5], [6], [9] and[12]. In case two or more types of photoacid generator are used inadmixture, combination of a compound of the formula [2], which has goodlight permeability at around 248.4 nm and is capable of maintaining hightransparency of resist material and which also has little PEBtemperature dependency and can generate a weak acid upon exposure tolight, and at least one compound selected from the group consisting ofthe compounds of the formulae [3], [5], [6], [9] and [12], which hashigh acid generating potency for a given rate of exposure and cangenerate a strong acid, is especially preferred in consideration of theimprovement of pattern shape at its tail and inhibition of scumming.

In the case of single use of a photoacid generator of the formula [12]which is very effective for preventing footing of the pattern orscumming, defective pattern formation may be caused due to delay time,but this problem can be overcome by applying overcoating. Also, changeof pattern size may take place in case of using a photoacid generator ofthe formula [12], but this can be prevented by increasing the ratio ofthe monomer unit of the formula [15] in the polymer of the formula [1].

Regarding the mixing ratio of the photoacid generators in case two ormore photoacid generators are used, a photoacid generator of the formula[3], [5], [6], [9] or [12] is added in a ratio of 1-70 parts by weight,preferably 10-50 parts by weight, to 100 parts by weight of a photoacidgenerator of the formula [2] as this range of ratio is most suited forinhibiting formation of scums or tails at the bottom of the pattern andallows stable maintenance of pattern shape and size without inducing theproblem of delay time.

Various triphenylsulfonium salts and diphenyliodonium salts (anions ofthese onium salts are PF₆ --, AsF₆ --, BF₄ --, etc.) andtris(trichloromethyl)-s-triazine/triethanolamine have been known asphotoacid generators beside those of the present invention, but whenthese photoacid generators are used singly in the production ofchemically amplified resist material, the generated acid may beevaporated away from the resist film surface after exposure and is alsovery susceptible to the influence of the atmosphere gas such as aminessince the acid (Lewis acid) generated on exposure is a strong acid andalso highly volatile, and consequently, with the lapse of time duringoperation from exposure to development, there arise the cumbrousproblems such as T-shaping of the formed pattern, large variation of thepattern shape and size, and no formation of a pattern. The aboveconventional photoacid generators also involve the problems relating tostorage stability, such as change of sensitivity during storage andfailure to form a pattern.

As for the solvent used in the present invention, any solvent can beused as far as it is capable of dissolving the polymers, photoacidgenerators and other additives such as ultraviolet absorbent andsurfactant used in the present invention, but usually it is recommendedto use a solvent having good film forming properties and showingabsorption at around 220-400 nm. Examples of such solvents include, butare not limited to, methyl cellosolve acetate, ethyl cellosolve acetate,propylene glycol monomethyl ether acetate, propylene glycol monoethylether acetate, methyl lactate, ethyl lactate, 2-ethoxyethyl acetate,methyl pyruvate, ethylpyruvate, methyl 3-methoxypropionate, ethyl3-methoxypropionate, N-methyl-2-pyrrolidone, cyclohexanone, methyl ethylketone, 2-heptanone, 1,4-dioxane, diethylene glycol monomethyl ether,diethylene glycol dimethyl ether and ethylene glycol monoisopropylether.

The resist material of the present invention usually consists of saidthree components (a polymer according to this invention, a photoacidgenerator and a solvent), but if necessary an ultraviolet absorbent maybe added. Ultraviolet absorbents usable in the present invention include9-diazofluorene and its derivatives, 1-diazo-2-tetralone,2-diazo-1-tetralone, 9-diazo-10-phenanthrone,9-(2-methoxyethoxy)methylanthracene, (2-ethoxyethoxy)methylanthracene,9-anthracenemethyl acetate, 9-anthracenemethyl propionate, etc.

It is also possible to add one or more of dye, sensitivity adjustor,plasticizer and surfactant which are commonly used in the art.

Sensitivity adjustors usable in this invention includepolyvinylpyridine, poly(vinylpyridine/methyl methacrylate), pyridine,piperidine, tetramethylammonium hydroxide, triethylamineandN-methyl-2-pyrrolidone.

Plasticizers include diethyl phthalate, dibutyl phthalate and dipropylphthalate.

Surfactants include nonionic surfactants and fluorine-containingnonionic surfactants.

The pattern forming process according to the present invention comprisesessentially the steps of coating the resist material described above ona substrate, heating and then exposing the coating film to light with awavelength of 300 nm or less through a mask, further heating the exposedcoating film as required, and developing it with a developing solution.

Pattern formation using the resist material according to the presentinvention can be accomplished, for example, in the following way.

Resist material of this invention is coated on a semiconductor substratesuch as silicon wafer to a coating thickness of 0.5-2.0 μm (about0.1-0.5 μm in case it is used as top layer of a 3-layer coat) andprebaked in an oven at 70°-130° C. for 10-30 minutes or on a hot plateat 70°-130° C. for 1-2 minutes. This resist film is exposed to deepultraviolet light of 300 nm or less at an exposure dose of about 1-100mJ/cm² through a mask for forming a desired pattern, then baked at70°-150° C. for 1-2 minutes and developed with a 0.1-5%tetramethylammonium hydroxide (TMAH) solution for about 0.5-3 minutes bya conventional method such as dipping, puddling or spraying to form thedesired pattern on the substrate.

The mixing ratio of polymer (a) and photoacid generator (b) in theresist material according to the present invention is 1-30 parts byweight, preferably 1-20 parts by weight of (b) to 100 parts by weight of(a). The amount of solvent (c) in the resist material of this inventionis not specifically defined as far as no impediment is caused when apositive resist material obtained by dissolving a polymer of thisinvention and a photoacid generator in the solvent is coated on asubstrate, but usually the ratio of solvent (c) is 100-2,000 parts byweight, preferably 150-1,000 parts by weight, to 100 parts by weight ofpolymer (a).

As developing solution used in the pattern forming processes such asdescribed above, an alkali solution of a suitable concentration that canenlarge the difference in degree of dissolution between the exposed andthe non-exposed portions is properly selected depending on thesolubility of resist material. Usually the concentration of said alkalisolution is selected from the range of 0.01-20%. The alkali solutionsusable as developer include the aqueous solutions containing organicamines such as TMAH, choline, triethanolamine, etc., or inorganicalkalis such as NaOH, KOH, etc.

The polymers according to the present invention, as described above,typically contain a monomer unit of the formula [14] having a functionalgroup of the formula [13], so that these polymers, as compared with theconventional polymers of the same type, have a greater disposition tobecome alkali-soluble with easier elimination of functional groups inthe presence of an acid. This is conducive to enhancement of resolvingperformance and stable maintenance of pattern shape and size throughtoutthe period of operation from exposure till heat treatment (baking).Further, the polymers according to the present invention, owing toincorporation of hydroxystyrene unit of the formula [16], have heatresistance, dry etch durability and high adhesiveness to the substrate.Also, the polymers according to the present invention, owing to itsmonomer unit of the formula [15], can control the developing speed atthe exposed portion to provide a sufficient focus margin and good masklinearity. They also contribute to smoothing the pattern side wall. Thenthis monomer unit also contributes to the improvement of heat resistanceof the polymer.

The monomer units represented by the formula [15] include those whichchange into hydroxystyrene unit soluble in alklai developing solution onelimination of the functional groups by the action of an acid (suchmonomer units including acetyloxy group, methoxy group, tert-butoxygroup, tetrahydrofuranyl group, tetrahydropyranyl group,tert-butoxycarbonyloxy group, tert-butoxycarbonylmethoxy group, etc.),but in the present invention the monomer unit of the formula [14] havinga functional group of the formula [13] can eliminate the functionalgroups far more fastly and easily under the action of an acid to becomehydroxystyrene unit.

JP-A-6-194842 (EPC Patent No. 0588544) discloses polymers consisting ofthree monomer units, but this patent concerns an electron ray resist anddiffers in its object from the present invention which relates to aresist material for forming a positive pattern by using deep ultravioletlight with a wavelength of 300 nm or less. Therefore, when a pattern isformed with ultraviolet light, such as KrF excimer laser light, by usingthe resist composition disclosed in the above patent, there arise suchproblems as poor resolution of the bottom portion of the pattern,formation of scums and their transfer during etching, so that thisresist composition is unsuited for pattern formation with ultravioletlight.

What is most remarkable in the present invention is the fact that bycombining a polymer consisting of three monomer units according to thepresent invention and a specific photoacid generator also disclosed bythe present invention, it has been realized to provide a resist materialwhich is freed of various problems encountered in conventional resistpattern formation using ultraviolet light such as deep ultraviolet lightor KrF excimer laser light, and which has various advantages alreadymentioned above and is suited for pattern formation by use of deepultraviolet light or KrF excimer laser light as exposure source.Further, the resist material of the present invention is effective foreliminating scums or tails at the bottom portion of the resist patternin case two or more types of photoacid generator according to thepresent invention are used in combination. This phenomenon can beaccounted for by the fact that a photoacid generator capable ofgenerating a stronger acid or capable of inducing greater acid diffusionhas a higher ability to eliminate the functional groups of the polymeruniformly down to the bottom of the resist. In view of this, thecombination of a photoacid generator of the formula [2] and a photoacidgenerator of the formula [3], [9] or [12] is considered to give the bestresult in application to the resist material according to the presentinvention.

The resist material of the present invention is best suited for patternformation by use of deep ultraviolet light or KrF excimer laser light,but it has been confirmed that an acid is also generated to inducechemical amplification on exposure to i-line light, electron beam orsoft X-rays, so that the resist material of the present invention can beused for forming a pattern by exposure to a small dose of deepultraviolet light, KrF excimer laser light, i-line light, electron beamor soft X-rays by making use of the chemically amplifying function ofthe material.

The principle of the present invention is described with reference toembodiments thereof.

When the resist film is exposed to KrF excimer laser light or deepultraviolet light, an acid is generated at the exposed portion accordingto the following formulae 1, 2, 3, 4 or 5: ##STR49##

When the exposed resist film is heated, a specific functional group(1-ethoxyethoxy group is exemplified in the formula 6) of the polymer ofthe present invention undergoes a chemical change by the generated acidaccording to the reaction of the following formula 6 to become ahydroxyl group, with the result that the polymer becomes alkali-solubleand is eluted out in the developing solution in the course ofdevelopment. ##STR50##

At the non-exposed portion, on the other hand, no chemical changesoccurs on heating since no acid is generated, and there is ratherinduced a phenomenon that the hydrophilic group moiety of the polymerused for the purpose of strengthening adhesion to the substrate isprotected against infiltration with the alkaline developing solution.Thus, when pattern formation is carried out using the resist material ofthe present invention, there is produced a large difference insolubility in alkaline developing solution between the exposed portionand the non-exposed portion, and further, since the polymer at thenon-exposed portion has strong adhesiveness to the substrate, no filmpeeling takes place during development, and consequently a positivepattern with good contrast is formed. It is also notable that since theacid generated on exposure according to the formula 6 acts in the mannerof a catalyst, there is no need of conducting exposure more thannecessary for generating a required acid, so that the amount of energyrequired for exposure can be reduced.

The present invention will be described in further detail with referenceto Examples, Synthesis Examples, Reference Examples and ComparativeExamples, but it should be noted that these examples are merely intendedto be illustrative and not to be construed as limiting the scope of theinvention.

Part of the photoacid generators used in the following Examples andComparative Examples were synthesized according to the methods describedin JP-A-4-210960 (U.S. Pat. No. 5,216,135), JP-A-4-211258 (U.S. Pat. No.5,350,660; EPC Patent 0,440,374), JP-A-5-249682 (EPC Patent 0,520,642),Y. Endo et al: Chem. Pharm. Bull., 29(12), 3753 (1981); M. Desbois etal: Bull. Chim. Soc. France, 1974, 1956, or C. D. Beard et al: J. Org.Chem., 38, 3673 (1973); Hashimoto et al: JPN Chem. Mag., 87(10), 1069(1966), etc.

SYNTHESIS EXAMPLE 1 Synthesis ofPoly[p-(1-ethoxyethoxy)styrene/p-hydroxystyrene/p-methylstyrene]

(1) A solution of p-tert-butoxystyrene (100 g, 0.567 mole) andp-methylstyrene (3.54 g, 0.03 mole) in 1,4-dioxane containing catalyticamount of 2,2'-azobis(methyl 2-methylpropionate) was polymerized at 80°C. for 6 hours under nitrogen. After cooling, the reaction mixture waspoured into aqueous methanol (5 l) and the polymer was precipitated. Thepolymer was filtered, washed with methanol and dried under reducedpressure to afford 92.3 g of poly(p-tert-butoxy-styrene/p-methylstyrene) as white powder having Mw 20000 (GPC with polystyrenecalibration). The polymer was found to have p-tert-butoxystyrene unitand p-methylstyrene unit in a molar ratio of ca. 95:5 based on ¹ HNMR.

(2) A solution of poly(p-tert-butoxystyrene/p-methylstyrene) (70 g)obtained in above (1) and conc. hydrochloric acid (100 ml) in1,4-dioxane was reacted for 4 hours at 70°-80° C. with stirring. Aftercooling, the reaction mixture was poured into H₂ O (5 l) and the polymerwas precipitated. The polymer was filtered, washed with H₂ O and driedunder reduced pressure to give 47.6 g ofpoly(p-hydroxystyrene/p-methylstyrene) as white powder. The polymer wasfound to have p-hydroxystyrene unit and p-methylstyrene unit in a molarratio of ca. 95:5 based on ¹ HNMR.

(3) To a solution of poly(p-hydroxystyrene/p-methylstyrene) (15.0 g)obtained in above (2) and ethyl vinyl ether (3.5 g) in 1,4-dioxane (150ml), a catalytic amount of pyridinium p-toluenesulfonate was added andreacted with stirring at room temperature for 24 hours. The reactionmixture was poured into H₂ O (5 l) and the polymer was precipitated. Theprecipitate was filtered, washed with H₂ O and dried under reducedpressure to afford 11.5 g ofpoly[p-(1-ethoxyethoxy)styrene/p-hydroxystyrene/p-methylstyrene] aswhite powder having Mw 20000 (GPC with polystyrene calibration). Thepolymer was found to have p-(1-ethoxyethoxy)styrene unit,p-hydroxystyrene unit and p-methylstyrene unit in a molar ratio of ca.35:60:5 based on ¹ HNMR.

SYNTHESIS EXAMPLE 2 Synthesis ofPoly[p-(1-ethoxyethoxy)styrene/p-hydroxystyrene/styrene]

(1) Using p-tert-butoxystyrene (81.1 g, 0.46 mole) and styrene (4.6 g,0.04 mole), the polymerization and the treatment were carried out in thesame manner as described in Synthesis Example 1, (1), to give 77.1 g ofpoly(p-tert-butoxystyrene/styrene) as white powders having Mw 20000 (GPCwith polystyrene calibration). The polymer was found to havep-tert-butoxystyrene unit and styrene unit in a molar ratio of ca. 92:8based on ¹ HNMR.

(2) Using poly(p-tert-butoxystyrene/styrene) (70 g) obtained in above(1), the reaction and the treatment were carried out in the same manneras described in Synthesis Example 1, (2), to afford 44.0 g ofpoly(p-hydroxystyrene/styrene) as white powder. The polymer was found tohave p-hydroxystyrene unit and styrene unit in a molar ratio of ca. 92:8based on ¹ HNMR.

(3) Using poly(p-hydroxystyrene/styrene) (15.0 g) obtained in above (2)and ethyl vinyl ether (3.2 g), the reaction and the treatment werecarried out in the same manner as described in Synthesis Example 1, (3),to give 14.1 g ofpoly[p-(1-ethoxyethoxy)styrene/p-hydroxystyrene/p-methylstyrene] aswhite powder having Mw 20000 (GPC with polystyrene calibration). Thepolymer was found to have p-(1-ethoxyethoxy)styrene unit,p-hydroxystyrene unit and styrene unit in a molar ratio of ca. 32:60:8based on ¹ HNMR.

SYNTHESIS EXAMPLE 3 Synthesis ofPoly[p-(1-ethoxyethoxy)styrene/p-hydroxystyrene/p-tert-butoxystyrene]

(1) A solution of p-tert-butoxystyrene (17.6 g) in iso-propanolcontaining catalytic amount of 2,2'-azobis(methyl 2-methylpropionate)was polymerized at 80° C. for 6 hours under nitrogen. After cooling, thereaction mixture was poured into aqueous methanol (1 l) and the polymerwas precipitated. The polymer was filtered, washed with methanol anddried under reduced pressure to give 16.7 g ofpoly(p-tert-butoxystyrene) as white powder having Mw 20000 (GPC withpolystyrene calibration).

(2) A suspension of poly(p-tert-butoxystyrene) (15.0 g) obtained inabove (1), and conc. hydrochloric acid (15 ml) in iso-propanol wasreacted for 4 hours at 70°-80° C. with stirring. After colling, thereaction mixture was poured into H₂ O (1 l) and the polymer wasprecipitated. The polymer was filtered, washed with H₂ O and dried underreduced pressure to give 9.6 g of poly(p-hydroxystyrene/p-tert-butoxystyrene) as white powder. The polymer was found to have p-hydroxystyreneunit and p-tert-butoxystyrene unit in a molar ratio of ca. 90:10 basedon ¹ HNMR.

(3) To a solution of poly(p-hydroxystyrene/p-tert-butoxystyrene) (15.7g) obtained in above (2) and ethyl vinyl ether (3.2 g) in 1,4-dioxane(140 ml), a catalytic amount of pyridinium p-toluenesulfonate was addedand reacted with stirring at room temperature for 24 hours. The reactionmixture was poured into H₂ O (3 l) and the polymer was precipitated. Theprecipitate was filtered, washed with H₂ O and dried under reducedpressure to give 16.0 g ofpoly[p-(1-ethoxyethoxystyrene/p-hydroxystyrene/p-tert-butoxystyrene] aswhite powder having Mw 20000 (GPC with polystyrene calibration). Thepolymer was found to have p-(1-ethoxyethoxy)styrene unit,p-hydroxystyrene unit and p-tert-butoxystyrene unit in a molar ratio ofca. 30:60:10 based on ¹ HNMR.

SYNTHESIS EXAMPLE 4 Synthesis ofPoly[p-(1-methoxy-1-methylethoxy)styrene/p-hydroxystyrene/p-tert-butoxystyrene]

To a solution of poly(p-hydroxystyrene/p-tert-butoxystyrene) (15.7 g)obtained in Synthesis Example 3, (2) and 2-methoxy-1-propene (3.2 g) intetrahydrofuran (120 ml), a catalytic amount of phosphorous oxychloridewas added and reacted with stirring for 16 hours at room temperature.After reaction, the reaction mixture was poured into H₂ O (5 l) and thepolymer was precipitated. The precipitate was filtered, washed with H₂ Oand dried under reduced pressure to afford 14.7 g ofpoly[p-(1-methoxy-1-methylethoxy)styrene/p-hydroxystyrene/p-tert-butoxystyrene]as white powder having Mw 20000 (GPC with polystyrene calibration). Thepolymer was found to have p-(1-methoxy-1-methylethoxy)styrene unit,p-hydroxystyrene unit and p-tert-butoxystyrene unit in a molar ratio ofca. 30:60:10 based on ¹ HNMR.

SYNTHESIS EXAMPLE 5 Synthesis ofPoly[p-(1-ethoxyethoxy)styrene/p-hydroxystyrene/p-methoxystyrene]

(1) Using p-tert-butoxystyrene (77.6 g, 0.44 mole) and p-methoxystyrene(8.1 g, 0.06 mole), the polymerization and treatment were carried out inthe same manner as described in Synthesis Example 1, (1), to give 77.1 gpoly(p-tert-butoxystyrene/p-methoxystyrene) as white powder having Mw20000 (GPC with polystyrene calibration). The polymer was found to havep-tert-butoxystyrene unit and p-methoxystyrene unit in a molar ratio ofca. 88:12 based on ¹ HNMR.

(2) Using poly (p-tert-butoxystyrene/p-methoxystyrene) (68.5 g) obtainedin above (1), the reaction and the treatment were carried out in thesame manner as described in Synthesis Example 1, (2), to give 43.9 g ofpoly (p-hydroxystyrene/p-methoxystyrene) as white powder. The polymerwas found to have p-hydroxystyrene unit and p-methoxystyrene unit in amolar ratio of ca. 88:12 based on ¹ HNMR.

(3) Using poly(p-hydroxystyrene/p-methoxystyrene) (15.2 g) obtained inabove (2) and ethyl vinyl ether (2.9 g), the reaction and the treatmentwere carried out in the same manner as described in Synthesis Example 1,(3), to afford 14.4 g ofpoly[p-(1-ethoxyethoxy)styrene/p-hydroxystyrene/p-methoxystyrene] aswhite powder having Mw 20000 (GPC with polystyrene calibration). Thepolymer was found to have p-(1-ethoxyethoxy)styrene unit,p-hydroxystyrene unit and p-methoxystyrene unit in a molar ratio of ca.30:58:12 based on ¹ HNMR.

SYNTHESIS EXAMPLE 6 Synthesis ofPoly[p-(1-benzyloxy-1-methylethoxystyrene/p-hydroxystyrene/p-tert-butoxystyrene]

(1) A solution of poly(p-tert-butoxystyrene) (15.0 g) obtained inSynthesis Example 3, (1) and conc. hydrochloric acid (20 ml) in1,4-dioxane was reacted with stirring for 4 hours at 70°-80° C. Aftercooling, the reaction mixture was poured into H₂ O (1 l) and the polymerwas precipitated. The precipitate was filtered, washed with H₂ O anddried under reduced pressure to give 9.4 g ofpoly(p-hydroxystyrene/p-tert-butoxystyrene) as white powder. The polymerwas found to have p-hydroxystyrene unit and p-tert-butoxystyrene unit ina molar ratio of ca. 95:5 based on ¹ HNMR.

(2) Using poly(p-hydroxystyrene/p-tert-butoxystyrene) (15.4 g) obtainedin above (1) and 1-benzyloxy-1-propene (5.9 g), the reaction and thetreatment were carried out in the same manner as described in SynthesisExample 4, to give 13.4 g ofpoly[p-(1-benzyloxy-1-methylethoxy)styrene/p-hydroxystyrene/p-tert-butoxystyrene]as white powder having Mw 20000 (GPC with polystyrene calibration). Thepolymer was found to have p-(1-benzyloxy-1-methylethoxy)styrene unit,p-hydroxystyrene unit and p-tert-butoxystyrene unit in a molar ratio ofca. 30:60:10 based on ¹ HNMR.

SYNTHESIS EXAMPLE 7 Synthesis ofPoly[p-(1-methoxyethoxy)styrene/p-hydroxystyrene/p-chlorostyrene]

(1) Using p-tert-butoxystyrene (83.7 g, 0.475 mole) and p-chlorostyrene(3.5 g, 0.025 mole), the polymerization and the treatment were carriedout in the same manner as described in Synthesis Example 1, (1), to give75.9 g of poly(p-tert-butoxystyrene/p-chlorostyrene) as white powderhaving Mw 22000 (GPC with polystyrene calibration). The polymer wasfound to have p-tert-butoxystyrene unit and p-chlorostyrene unit in amolar ratio of ca. 95:5 based on ¹ HNMR.

(2) Using poly(p-tert-butoxystyrene/p-chlorostyrene) (61.0 g) obtainedin above (1), the reaction and the treatment were carried out in thesame manner as described in Synthesis Example 1, (2), to give 36.0 g ofpoly(p-hydroxystyrene/p-chlorostyrene) as white powder. The polymer wasfound to have p-hydroxystyrene unit and p-chlorostyrene unit in a molarratio of ca. 95:5 based on ¹ HNMR.

(3) Using poly(p-hydroxystyrene/p-chlorostyrene) (15.1 g) obtained inabove (2) and methyl vinyl ether (2.9 g), the reaction and the treatmentwere carried out in the same manner as described in Synthesis Example 1,(3), to give 14.1 g ofpoly[p-(1-methoxyethoxy)styrene/p-hydroxystyrene/p-chlorostyrene] aswhite powder having Mw 22000 (GPC with polystyrene calibration). Thepolymer was found to have p-(1-methoxyethoxy)styrene unit,p-hydroxystyrene unit and p-chlorostyrene unit in a molar ratio of ca.35:60:5 based on ¹ HNMR.

SYNTHESIS EXAMPLE 8 Synthesis ofPoly[p-(1-ethoxyethoxy)styrene/p-hydroxystyrene/p-acetyloxystyrene]

(1) Using p-acetyloxystyrene (32.4 g), the polymerization and thetreatment were carried out in the same manner as described in SynthesisExample 3, (1), to give 30.0 g of poly(p-acetyloxystyrene) as whitepowders having Mw 15000 (GPC with polystyrene calibration).

(2) A solution of poly(p-acetyloxystyrene) (13.8 g) obtained in above(1) and conc. hydrochloric acid (5 ml) in 1,4-dioxane was reacted withstirring for 2 hours at 70°-80° C. After cooling, the reaction mixturewas poured into H₂ O (1 l) and the polymer was precipitated. The polymerwas filtered, washed with H₂ O and dried under reduced pressure to give9.5 g of poly(p-hydroxystyrene/p-acetyloxystyrene) as white powder. Thepolymer was found to have p-hydroxystyrene unit and p-acetyloxystyreneunit in a molar ratio of ca. 90:10 based on ¹ HNMR.

(3) Using poly(p-hydroxystyrene/p-acetyloxystyrene) (9.5 g) obtained inabove (2) and ethyl vinyl ether (2.2 g), the reaction was carried out inthe same manner as described in Synthesis Example 3, (3), theprecipitate was filtered, washed with H₂ O and dried under reducedpressure to give 9.9 g ofpoly[p-(1-ethoxyethoxy)styrene/p-hydroxystyrene/p-acetyloxystyrene] aswhite powder having Mw 17500 (GPC with polystyrene calibration). Thepolymer was found to have p-(1-ethoxyethoxy)styrene unit,p-hydroxystyrene unit and p-acetyloxystyrene unit in a molar ratio ofca. 35:55:10 based on ¹ HNMR.

SYNTHESIS EXAMPLE 9 Synthesis ofPoly[p-(1-ethoxyethoxy)styrene/p-hydroxystyrene/p-tetrahydropyranyloxystyrene]

(1) A solution of p-acetyloxystyrene (16.2 g) obtained in SynthesisExample 8, (1) and conc. hydrochloric acid (25 ml) in 1,4-dioxane wasreacted with stirring for 4 hours under reflux. After cooling, thereaction mixture was poured into H₂ O (1 l) and the polymer wasprecipitated. The precipitate was filtered, washed with H₂ O and driedunder reduced pressure to give 11.4 g of poly(p-hydroxystyrene) as whitepowder.

(2) A solution of poly(p-hydroxystyrene) (10.8 g) obtained in above (1),2,3-dihydropyran (1.5 g) and pyridinium p-toluenesulfonate (0.05 g) in1,4-dioxane was reacted with stirring for 15 hours at 25°-30° C. Afterreaction, the reaction mixture was poured into H₂ O (1 l) and thepolymer was precipitated. The precipitate was filtered, washed with H₂ Oand dried under reduced pressure to afford 10.0 g ofpoly(p-hydroxystyrene/p-tertahydropyranyloxystyrene) as white powder.The polymer was found to have p-hydroxystyrene unit andp-tetrahydropyranyloxystyrene unit in a molar ratio of ca. 92:8 based on¹ HNMR.

(3) Using poly(p-hydroxystyrene/p-tetrahydropyranyloxystyrene) (9.5 g)obtained in above (2) and ethyl vinyl ether (2.1 g), the reaction wascarried out in the same manner as described in Synthesis Example 3, (3),the precipitate was filtered, washed with H₂ O and dried under reducedpressure to give 9.9 g ofpoly[p-(1-ethoxyethoxy)styrene/p-hydroxystyrene/p-tetrahydropyranyloxystyrene]as white powder having Mw 17000 (GPC with polystyrene calibration). Thepolymer was found to have p-(1-ethoxyethoxy)styrene unit,p-hydroxystyrene unit and p-tetrahydropyranyloxystyrene unit in a molarratio of ca. 32:60:8 based on ¹ HNMR.

SYNTHESIS EXAMPLE 10 Synthesis ofPoly[p-(1-ethoxyethoxy)styrene/p-hydroxystyrene/p-tert-butoxycarbonyloxystyrene]

(1) A suspension of ply(p-tert-butoxystyrene) (35.3 g) obtained insynthesis Example 3, (1) and conc. hydrochloric acid (50 ml) iniso-propanol was reacted with stirring for 4 hours under reflux. Aftercooling, the reaction mixture was poured into H₂ O (3 l) and the polymerwas precipitated. The polymer was filtered, washed with H₂ O and driedunder reduced pressure to afford 22.1 g of poly(p-hydroxystyrene) aswhite powder.

(2) To a solution of poly(p-hydroxystyrene) (16.2 g) obtained in above(1) in ethyl acetate (60 ml), di-tert-butyl dicarbonate (3.3 g) andanhydrous potassium carbonate (2.5 g) were added and reacted withstirring for 4 hours at room temperature. After reaction, ethyl acetatewas removed in vacuo, the residue was diluted with acetone (80 ml), andthen the solution was poured into H₂ O (1 l). The resultant precipitatewas filtered, washed with H₂ O and dried under reduced pressure to give12.1 g of poly(p-hydroxystyrene/p-tertbutoxycarbonyloxystyrene) as whitepowder. The polymer was found to have p-hydroxystyrene unit andp-tert-butoxycarbonyloxystyrene unit in a molar ratio of ca. 91:9 basedon ¹ HNMR.

(3) Using poly(p-hydroxystyrene/p-tert-butoxycarbonyloxystyrene) (11.4g) obtained in above (2) and ethyl vinyl ether (2.5 g), the reaction andthe treatment were carried out in the same manner as described inSynthesis Example 1, (3), to give 6.8 g ofply[p-(1-ethoxyethoxy)styrene/p-hydroxystyrene/p-tert-bugtoxycarbonyloxystyrene]as white powder having Mw 21500 (GPC with polystyrene calibration). Thepolymer was found to have p-(1-ethoxyethoxy)styrene unit,p-hydroxystyrene unit and p-tert-butoxycarbonyloxystyrene unit in amolar ratio of ca. 30:61:9 based on ¹ HNMR.

SYNTHESIS EXAMPLE 11 Synthesis ofPoly[p-(1-methoxyethoxy)styrene/p-hydroxystyrene/tert-butylp-vinylphenoxyacetate]

(1) A suspension of poly(p-hydroxystyrene) (16.2 g) obtained inSynthesis Example 10, (1), tert-butyl monochloroacetate (3.0 g) andanhydrous potassium carbonate (2.8 g) in acetone (200 ml) was reactedwith stirring for 2 hours under reflux. After cooling, the inorganicprecipitate was filtered off, the filtrate was poured into H₂ O (3 l)and the polymer was precipitated. The precipitate was filtered, washedwith H₂ O and dried under reduced pressure to give 15.8 g ofpoly(p-hydroxystyrene/tert-butyl p-vinylphenoxyacetate) as white powder.The polymer was found to have p-hydroxystyrene unit and tert-butylp-vinylphenoxyacetate unit in a molar ratio of ca. 90:10 based on ¹HNMR.

(2) Using poly(p-hydroxystyrene/tert-butyl p-vinylphenoxyacetate) (13.2g) obtained in above (1) and methyl vinyl ether (2.0 g), the reactionand the treatment were carried out in the same manner as described inSynthesis Example 1, (3), to give 10.6 g ofpoly[p-(1-methoxyethoxy)styrene/p-hydroxystyrene/tert-butylp-vinylphenoxyacetate] as white powder having Mw 21000 (GPC withpolystyrene calibration). The polymer was found to havep-(1-methoxyethoxy)styrene unit, p-hydroxystyrene unit and tert-butylp-vinylphenoxyacetate unit in a molar ratio of ca. 35:55:10 based on ¹HNMR.

SYNTHESIS EXAMPLE 12 Synthesis of1,2,3-tris(trifluoromethanesulfonyloxy)benzene

To a suspension of 1,2,3-benzenetriol (1.01 g, 8.01 mmole) andγ-collidine (4.14 g, 32.3 mmole) in methylene chloride (60 ml),trifluoromethanesulfonic anhydride (8.13 g, 28.8 mmole) was addeddropwise at -3°-0°° C. and stirring was continued for 6 hours at thesame temperature. After reaction, H₂ O (50 ml) and toluene (50 ml) wereadded to the mixture with stirring and standed. The organic layer wasseparated, washed with 5% sodium hydroxide aqueous solution (50 ml) thenH₂ O (50 ml), dried over anhydrous MgSO₄ and evaporated. The residue waschromatographed on silica gel (Wakogel C-200, manufactured by Wako pureChemical Industries, Ltd.) with n-hexane/ethyl acetate [1/20 (v/v)] aseluent to give 1.82 g of 1,2,3-tris(trifluoromethanesulfonyloxy)benzeneas white crystals. m.p. 47.5°-48.5° C.

¹ HNMR δ ppm (CDCl₃): 7.59 (3H, s, Aromatic).

IR (KBr-disk) νcm⁻¹ : 3116, 1137.

SYNTHESIS EXAMPLE 13 Synthesis of2,3,4-tris(trifluoromethanesulfonyloxy)acetophenone

Using 2,3,4-trihydroxyacetophenone (1.68 g, 10 mmole) andtrifluoromethanesulfonic anhydride (9.88 g, 35 mmole), the reaction andthe treatment were carried out in the same manner as described inSynthesis Example 12, the resultant crude yellow oil (5.3 g) waschromatographed on silica gel (Wakogel C-200) with n-hexane/methylenechloride (2/1) as eluent to give 2.77 g of2,3,4-tris(trifluoromethanesulfonyloxy)acetophenone as white crystals.m.p. 74.8°-76.4° C.

¹ HNMR δ ppm (CDCl₃): 2.68 (3H, s, CH₃), 7.67 (1H, d, J=8.8Hz), 7.,89(1H, d, J=8.8 Hz).

IR (KBr-disk) νcm⁻¹ : 3403, 3108, 2937, 1715, 1607, 1363 (SO₂), 1123(SO₂).

SYNTHESIS EXAMPLE 14 Synthesis of2,2',4,4'-tetra(trifluoromethanesulfonyloxy)benzophenone

Using 2,2',4,4'-tetrahydroxybenzophenone (2.46 g, 10 mmole) andtrifluoromethanesulfonic anhydride (13.3 g, 47 mmole), the reaction andthe treatment were carried out in the same manner as described inSynthesis Example 12, the resultant crude yellow oil (7.7 g) waschromatographed on silica gel (Wakogel C-200) with n-hexane/methylenechloride [7/3 (v/v)] as eluent to give 2.1 g of2,2',4,4'-tetra-(trifluoromethanesulfonyloxy)benzophenone as pale yellowcrystals. m.p. 94.0°-96.0° C.

¹ HNMR δ ppm (CDCl₃): 7.35 (2H, d, J=2.20 Hz, Aromatic), 7.51 (2H, dd,J=2.20 Hz and J=8.43 Hz, Aromatic), 7.88 (2H, d, J=8.43 Hz, Aromatic).

IR (KBr-disk) νcm⁻¹ : 3091, 1683, 1609, 1138 (SO₂).

SYNTHESIS EXAMPLE 15 Synthesis of1,2,3-tris(2,2,2-trifluoroethanesulfonyloxy)benzene

To a suspension of 1,2,3-benzenetriol (2.30 g, 18 mmole) andtriethylamine (6.53 g, 64.5 mmole) in methylene chloride (80 ml),2,2,2-trifluoroethanesulfonyl chloride (11.65 g, 64 mmole) was addeddropwise at -5°-0° C., continued to stir for 2 hours at the sametemperature and standed at room temperature overnight. The reactionmixture was poured into cold H₂ O (120 ml), extracted with methylenechloride (80 ml), the organic layer was washed with saturated sodiumbicarbonate aqueous solution (80 ml×l), then H₂ O (80 ml×l), dried overanhydrous MgSO₄ and evaporated. The residual oil (8.3 g) waschroamtographed on silica gel (Wakogel C-200, manufactured by Wako PureChemical Industries, Ltd.) with n-hexane/ethyl acetate [8/1 (v/v)] aseluent and recrystallized from n-hexane/methylene chloride [2/1 (v/v)]to give 1.2 g of 1,2,3-tris(2,2,2-trifluoroethanesulfonyloxy)benzene aswhite leaflets. m.p. 73.5°-75.0° C.

¹ HNMR δ ppm (DMSO-d₆): 5.23-5.50 (6H, m, CH₂ ×3), 7.65-7.76 (3H, m,Aromatic).

IR (KBr-disk) νcm⁻¹ : 3022, 2968, 1334 (SO₂), 1156 (SO₂).

SYNTHESIS EXAMPLE 16 Synthesis of2,3,4-tris(2,5-dichlorobenzenesulfonyloxy)acetophenone

To a solution of 2,3,4-trihydroxyacetophenone (1.18 g, 7 mmole) andtriethylamine (2.02 g, 20 mmole) in methylene chloride (20 ml), asolution of 2,5-dichlorobenzenesulfonyl chloride (4.90 g, 20 mmole) inmethylene chloride (10 ml) was added dropwise at 0°-2° C. and reactedwith stirring for 1 hour at the same temperature. The reaction mixturewas poured into ice-cold H₂ O (100 ml), extracted with methylenechloride (100 ml×2), the organic layer was washed with H₂ O (100 ml×2),dried over anhydrous MgSO₄ and evaporated. The residue (7.3 g) wasrecrystallized from methanol to give 3.0 g of2,3,4-tris(2,5-dichlorobenzenesulfonyloxy)acetophenone as whitecrystals. m.p. 165.0°-166.5° C.

¹ HNMR δ ppm (DMSO-d₆): 3.43 (3H, s, CH₃ CO), 7.46 (1H, d, J=9 HzAromatic), 7.64 (1H, d, J=8 Hz, Aromatic), 7.79-7.98 (9H, m, Aromatic)

IR (KBr-disk) νcm⁻¹ : 1730 (C═O), 1190 (SO₂)

SYNTHESIS EXAMPLE 17 Synthesis of diphenyl-p-tolylsulfoniumperfluorooctanesulfonate

To a solution of diphenylsulfoxide (2.02 g, 10 mmole) in toluene (30ml), trifluoroacetic anhydride (4.2 g, 20 mmole) was added dropwise at10° C. or below, then perfluorooctanesulfonic acid (5.0 g, 10 mmole) wasadded to the mixture, reacted with stirring for 1 hour at 10° C. orbelow, and then for 2 hours at room temperature. After standing, theoily layer was separated, washed with toluene (30 ml×2) and withn-hexane (30 ml×3) to afford 7.4 g of diphenyl-p-tolylsulfoniumperfluorooctanesulfonate as yellow viscous oil.

¹ HNMR δ ppm (CDCl₃): 2.44 (3H, s, CH₃), 7.46 (2H, d, J=8 Hz, Aromatic),7.60 (2H, d, J=8 Hz, Aromatic), 7.65-7.73 (10H, m, Aromatic).

SYNTHESIS EXAMPLE 18 Synthesis of Triphenylsulfonium p-toluenesulfonate

(1) To a suspension of magnesium turning (12 g) in ethyl ether (500 ml),bromobenzene (83.5 g, 0.54 mole) was added dropwise under reflux withstirring and continued to stir for 1 hour under reflux. to this Grignardreagent, benzene (500 ml) was added and concentrated until 500 ml. Tothis resultant mixture, a solution of diphenylsulfoxide (30 g, 0.15mole) in benzene (200 ml) was added and reacted with stirring for 40hours under reflux. After the reaction mixture was cooled to 0° C., 40%tetrafluoroboric acid (50 ml) was added dropwise at 0°-5° C. and reactedwith stirring for 5 hours at the same temperature. After standing atroom temperature overnight, the aqueous layer separated was extractedwith methylene chloride (100 ml×3), the organic layer was washed with H₂O, dried over anhydrous sodium sulfate and dried. The residual crudesolid was recrystallized from chloroform/ethyl ether to give 28 g oftriphenylsulfonium tetrafluoroborate as white crystals. m.p. 291°-292°C.

(2) To a solution of triphenylsulfonium tetrafluoroborate (1.0 g, 3mmole) obtained in above (1) in ethanol (180 ml), a solution of sodiump-toluenesulfonate (0.58 g, 3 mmole)in H₂ O (20 ml) was added withvigorous stirring at room temperature and continued to stir for 2 hoursat room temperature. After standing at room temperature overnight, theprecipitate was filtered off, the filtrate was concentrated underreduced pressure and the residue was recrystallized from methanol/ethylether to give 1.15 g of triphenylsulfonium p-toluenesulfonate as whiteneedles. m.p. 100°-102° C.

SYNTHESIS EXAMPLE 19 Synthesis of Triphenylsulfonium 10-camphorsulfonate

To a solution of triphenylsulfonium tetrafluoroborate (1.0 g, 3 mmole)obtained in Synthesis Example 18, (1) in acetone (50 ml), a solution ofpotassium 10-camphorsulfonate (0.80 g, 3 mmole) in H₂ O (10 ml) wasadded with vigorous stirring at room temperature and continued to stirfor 1 hour at room temperature. After standing at room temperatureovernight, the precipitate was filtered off, the filtrate wasconcentrated under reduced pressure and the residue was recrystallizedfrom methanol/ethyl ether to afford 1.20 g of triphenylsulfonium10-camphorsulfonate as white needles having a melting point of 66° C.(dec.).

REFERENCE EXAMPLE 1 Synthesis ofPoly(p-1-ethoxyethoxystyrene/p-hydroxystyrene)

(1) A solution of p-tert-butoxystyrene (17.6 g) in toluene containingcatalytic amount of 2,2'-azobisisobutyronitrile was polymerized at 80°C. for 6 hours under nitrogen. After cooling, the reaction mixture waspoured into methanol (1 l) and the polymer was precipitated. The polymerwas filtered, washed with methanol and dried under reduced pressure toafford 16.8 g of poly(p-tert-butoxystyrene) as white powder having Mw10000 (GPC with polystyrene calibration).

(2) A solution of poly(p-tert-butoxystyrene) (15.0 g) obtained in above(1) and conc. hydrochloric acid (10 ml) in 1,4-dioxane was refluxed for4 hours with stirring. The mixture was cooled, poured into H₂ O (1 l)and the solid was precipitated. The polymer was filtered, washed with H₂O and dried under reduced pressure to give 9.7 g ofpoly(p-hydroxystyrene) as white powder.

(3) To a solution of poly(p-hydroxystyrene) (4.0 g) obtained in above(2) and ethyl vinyl ether (1.2 g) in a mixed solvent (35 ml) of1,4-dioxane and pyridine, a catalytic amount of p-toluenesulfonic acidwas added and reacted with stirring at room temperature for 24 hours.The reaction mixture was poured into H₂ O (1 l) and a white solid wasprecipitated. The polymer was filtered, washed with h₂ O and dried underreduced pressure to afford 5.0 g ofpoly[p-(1-ethoxyethoxy)styrene/p-hydroxystyrene] as white powder havingMw 10000 (GPC with polystyrene calibration). The polymer was found tohave p-(1-ethoxyethoxy)styrene unit and p-hydroxystyrene unit in a molarratio of ca. 4:6 based on ¹ HNMR.

REFERENCE EXAMPLE 2 Synthesis ofPoly(p-tetrahydropyranyloxystyrene/p-hydroxystyrene)

To a solution of poly(p-hydroxystyrene) (9.0 g) obtained in ReferenceExample 1, (2) in 1,2-dimethoxyethane (100 ml) 2,3-dihydroxypyran (12.6g) and sulfuric acid (0.5 ml) were added, followed by reaction at30°-40° C. for 15 hours with stirring. After reaction, the mixture wasevaporated in vacuo, the residue was neutralized by addition of sodiumcarbonate and poured into H₂ O (1 l) to precipitate a polymer. Thepolymer was filtered by suction, washed with H₂ O and dried underreduced pressure to give 11.0 g ofpoly(p-tetrahydropyranyloxystyrene/p-hydroxystyrene) as white powderhaving Mw 10000 (GPC with polystyrene calibration). The polymer wasfound to have p-tetrahydropyranyloxystyrene unit and p-hydroxy styreneunit in a molar ratio of ca. 3:7 based on ¹ HNMR.

REFERENCE EXAMPLE 3 Synthesis ofPoly(p-tert-butoxycarbonyloxystyrene/p-hydroxystyrene)

(1) A solution of p-tert-butoxycarbonyloxystyrene (22 g, 0.1 mole)obtained by the method of U.S. Pat. No. 4,491,628 (1985) in toluenecontaining catalytic amount of 2,2'-azobis(2,4-dimethylvaleronitrile)was polymerized at 90° C. for 4 hours under nitrogen. After cooling, thereaction mixture was poured into methanol and the polymer wasprecipitated. The polymer was filtered, washed with methanol and driedunder reduced pressure to give 15.2 g ofpoly(p-tert-butoxycarbonyloxystyrene) as white powder having Mw 12000(GPC with polystyrene calibration).

(2) To a solution of poly(p-tert-butoxycarbonyloxystyrene) (7.0 g)obtained in above (1) in 1,4-dioxane, conc. hydrochloric acid (5 ml) wasadded and continued to stir under reflux for 2 hours. After cooling, thereaction mixture was poured into H₂ O (1 l) and the polymer wasprecipitated. The polymer was filtered by suction, washed with H₂ O anddried under reduced pressure to give 4.8 g ofpoly(p-tert-butoxycarbonyloxystyrene/p-hydroxystyrene) as white powderhaving Mw 10000 (GPC with polystyrene calibration). The polymer wasfound to have p-tert-butoxycarbonyloxystyrene unit and p-hydroxystyreneunit in a molar ratio of ca. 4:6 based on ¹ HNMR.

REFERENCE EXAMPLE 4 Synthesis ofPoly(p-tert-butoxystyrene/p-hydroxystyrene)

A solution of poly(p-tert-butoxystyrene) (15.0 g) obtained in ReferenceExample 1, (1) and conc. hydrochloric acid (10 ml) in 1,4-dioxane wasreacted for 3 hours at 80°-85° C. with stirring. After reaction, thereaction mixture was poured into H₂ O and the polymer was precipitated.The polymer was filtered by suction, washed with H₂ O and dried underreduced pressure to give 9.8 g ofpoly(p-tert-butoxystyrene/p-hydroxystyrene) as white powder having Mw9000 (GPC with polystyrene calibration). The polymer was found to havep-tert-butoxystyrene unit and p-hydroxystyrene unit in a molar ratio ofca. 35:65 based on ¹ HNMR.

REFERENCE EXAMPLE 5 Synthesis of 9-diazo-10-phenanthrone

A suspension of 9,10-phenanthrenequinone (2.08 g, 20 mmole) andp-toluenesulfonylhydrazide (1.80 g, 19 mmole) in ethanol (20 ml) wasrefluxed for 10 minutes with stirring. After cooling, the precipitatewas filtered and recrystallized from cyclohexane/petroleum ether to give1.1 g of 9-diazo-10-phenan throne as yellow needles having a m.p.107°-109° C.

IR (KBr-disk) νcm⁻¹ : 2106 (CN₂), 1615 (C═O).

REFERENCE EXAMPLE 6 Synthesis of 1-diazo-2-tetralone

To a solution of sodium ethoxide (20.0 g, 0.20 mole) in ethanol (600ml), a solution of 2-tetralone (42.4 g, 0.29 mole) in ethanol (100 ml)was added dropwise at 0° C. with stirring, then p-toluenesulfonylazide(59.2 g, 0.3 mole) was added dropwise at -15° C. or below to the mixtureand reacted with stirring for 3 hours at -10° to 0° C. The reactionmixture was poured into H₂ O (1 l), extracted with methylene chloride(500 ml×2), the organic layer separated was washed with H₂ O (500 ml×3),dried over anhydrous MgSO₄ and evaporated. The oily residue (72 g) waschromatographed on silica gel (Wakogel C-200) withn-hexane-n-hexane/methylene chloride (1/1) as eluent and recrystallizedfrom n-hexane to afford 6.0 g of 1-diazo-2-tetralone as yellow crystals.m.p. 42.5°-44.2° C.

¹ HNMR δ ppm (CDCl₃): 2.66 (2H, t, J=7 Hz), 3.02 (2H, t, J=7 Hz), 6.98(1H, d, J=8 Hz), 7.10 (1H, t, J=8 Hz), 7.21-7.29 (2H, m)

IR (Neat) νcm⁻¹ : 2080 (CN₂)

REFERENCE EXAMPLE 7 Synthesis of 2-diazo-1-tetralone

(1) A solution of α-tetralone (4.4 g, 30 mmole) in ethanol (30 ml) wascooled to 10° C., 90% potassium tert-butoxide (4.5 g, 36 mmole) wasadded to a solution and continued to stir for 30 minutes at 10° C. Thenisoamyl nitrite (3.5 g, 30 mmole) was added dropwise at 10° C. to thesolution and reacted with stirring for 5 hours at the same temperature.The reaction mixture was poured into H₂ O, neutralized with conc.hydrochloric acid, extracted with methylene chloride, the organic layerwas separated and evaporated. The residual dark-brownish oil (6.7 g) wascrystallized from n-hexane, the crystals was filtered and dried to give2.3 g of 2-oxyimino-1-tetralone as dark-brown crystals.

¹ HNMR δ ppm (CDCl₃): 3.07 (2H, t, J=6 Hz), 3.18 (2H, t, J=6 Hz), 7.30(1H, d, J=8 Hz), 7.38 (1H, t, J=8 Hz), 7.54 (1H, t, J=8 Hz), 8.12 (1H,d, J=8 Hz).

(2 ) A suspension of 2-oxyimino-1-tetralone (1.2 g, 7 mmole) obtained inabove (1) and sodium hydroxide (0.4 g, 10 mmole) in H₂ O (10 ml), 25%ammonia water (4 ml) was added dropwise at 10° C. or below, thenhypochlorous acid (30 ml) was added dropwise to the mixture at 10° C. orbelow and reacted with stirring for 1 hour at 10° C. After reaction, theprecipitate was filtered, washed with H₂ O and dried. The resultantsolid (0.90 g) was dissolved in methylene chloride, treated with activecarbon, evaporated and the residue was recrystallized from n-hexane togive 0.55 g of 2-diazo-1-tetralone as yellow crystals. m.p. 50.0°-52.0°C.

¹ HNMR δppm (CDCl₃): 3.01 (4H, m), 7.21 (1H, d, J=7 Hz), 7.36 (1H, t,J=7 Hz), 7.42 (1H, t, J=7 Hz), 8.01 (1H, d, J=8 Hz).

IR (KBr-disk) νcm⁻¹ : 2073 (CN₂), 1629 (C═O).

REFERENCE EXAMPLE 8 Synthesis of 9-diazofluorenone

(1) To a suspension of p-toluenesulfonylhydrazide (3.7 g, 20 mmole) inethanol (60 ml), 9-fluorenone (3.6 g, 20 mmole) was added and reactedfor 6 hours under reflux. After cooling, the precipitate was filteredand dried to give 5.4 g of 9-fluorenone p-toluenesulfonylhydrazide aspale yellow needles. m.p. 173°-174° C.

IR (KBr-disk) νcm⁻¹ : 3212, 3065, 1909, 1597, 1453, 1407, 1337, 1315.

(2) A suspension of 9-fluorenone p-toluenesulfonylhydrazide (1.7 g, 5mmole) obtained in above (1) and sodium ethoxide (0.3 g, 5 mmole) inpyridine (20 ml) was reacted with stirring for 6 hours at 60°-65° C. Thereaction mixture was poured into ice-cold H₂ O (100 ml), extracted withmethylene chloride and the organic layer separated was evaporated. Theresidual brown oil was chromatographed on silica gel (Wakogel C-200,manufactured by Wako Pure Chemical Industries, Ltd.) with ethylacetate/n-hexane (1/10) as eluent to give 0.6 g of 9-diazofluorenone asorange yellow needles. m.p. 98.5°-99.5° C.

¹ HNMR δppm (CDCl₃): 7.32 (2H, t, J=8 Hz), 7.39 (2H, t, J=8 Hz), 7.51(2H, d, J=8 Hz), 7.94 (2H, d, J=8 Hz).

IR (KBr-disk) νcm⁻¹ : 2087 (CN₂)

SYNTHESIS EXAMPLE 9 Synthesis of 9-(2-methoxyethoxy)methylanthracene

To a solution of 2-methoxyethanol (1 l) in benzene (1.5 l), conc.sulfuric acid (3 ml) was added and the mixture was heated to 80° C. Asolution of 9-anthracenemethanol (45 g, 0.22 mole) in 2-methoxyethanol(450 ml) was added to the mixture under reflux and stirring wascontinued for 1.5 hours under reflux. After standing at room temperatureovernight, the reaction mixture was washed with saturated aqueous sodiumbicarbonate, dried over anhydrous MgSO₄ and evaporated. The residualcrude oil (63 g) was chromatographed on silica gel (Wakogel C-200,manufactured by Wako Pure Chemical Industries, Ltd.) with n-hexane/ethylacetate [50/1→25/1→8/1 (V/V)] as eluent to give 47.6 g of9-(2-methoxyethoxy)methylanthracene as orange yellow oil.

¹ HNMR δppm (CDCl₃): 3.37 (3H, s, CH₃ O), 3.53-3.57 (2H, t, CH₃, O--CH₂--), 3.73-3.77 (2H, t, CH₃ O--CH₂ CH₂ O), 5.55 (2H, s, Ar--CH₂ O--),7.43-7.56 (4H, m, Aromatic 2-H, 3-H, 6-H, 7-H), 7.99 (2H, d, J=9 Hz,Aromatic 4-H, 5-H), 8.42 (2H, d, J=9 Hz, Aromatic 1-H, 8-H), 8.44 (1H,s, Aromatic 10-H).

IR (Neat) νcm⁻¹ : 1130.

REFERENCE EXAMPLE 10 Synthesis of poly(tert-butylp-vinylphenoxyacetate/p-hydroxystyrene)

A suspension of poly(p-hydroxystyrene) (4.0 g) obtained in the samemanner as described in Reference Example 1, (2), tert-butylmonochloroacetate (3.0 g) and anhydrous K₂ CO₃ (2.8 g) in acetone (35ml) was reacted with stirring for 2 hours under reflux. After cooling,the precipitate was filtered off, the filtrate was poured into H₂ O (1l) and was precipitated. The precipitate was filtered, washed with H₂ Oand dried under reduced pressure to give 5.2 g of poly(tert-butylp-vinylphenoxyacetate/p-hydroxystyrene) as white powder having Mw 11000(GPC with polystyrene calibration). The polymer was found to havetert-butyl p-vinylphenoxyacetate unit and p-hydroxystyrene unit in amolar ratio of ca. 1:1 based on ¹ HNMR.

REFERENCE EXAMPLE 11 Synthesis ofPoly[p-(1-ethoxyethoxy)styrene/p-hydroxystyrene/fumaronitrile]

(1) A solution of p-tert-butoxystyrene (28.2 g, 0.16 mole) andfumaronitrile (3.1 g, 0.04 mole) in toluene containing catalytic amountof 2,2'-azobis(methyl 2-methylpropionate) was polymerized at 90° C. for2 hours under nitrogen. After cooling, the reaction mixture was pouredinto methanol and the polymer was precipitated. The polymer wasfiltered, washed with methanol and dried under reduced pressure toafford 21.3 g of poly(p-tert-butoxystyrene/fumaronitrile) as whitepowder.

(2) Using poly(p-tert-butoxystyrene/fumaronitrile) (20.0 g) obtained inabove (1), the reaction and the treatment were carried out in the samemanner as described in Reference Example 1, (2) to give 10.6 g ofpoly(p-hydroxystyrene/fumaronitrile) as white powder having Mw 10000(GPC with polystyrene calibration).

(3) Using poly(p-hydroxystyrene/fumaronitrile) (9.0 g) and ethyl vinylether (3.0 g), the reaction and the treatment were carried out in thesame manner as described in Reference Example 1, (3) to afford 8.8 g ofpoly[p-(1-ethoxyethoxy)styrene/p-hydroxystyrenefumaronitrile) as whitepowder having Mw 11000 (GPC with polystyrene calibration). The polymerwas found to have p-(1-ethoxyethoxy)styrene unit and p-hydroxystyreneunit in a molar ratio of ca. 4:6 based on ¹ HNMR.

REFERENCE EXAMPLE 12 Synthesis ofPoly[p-(1-methoxyethoxy)styrene/p-hydroxy styrene]

Using poly(p-hydroxystyrene) (4.0 g) obtained in the same manner asdescribed in Reference Example 1, (2) and methyl vinyl ether (4.0 g),the reaction and the treatment were carried out in the same manner asdescribed in Reference Example 1, (3) to give 5.3 g ofpoly[p-(1-methoxyethoxy)styrene/p-hydroxystyrene] as white powder havingMw 10000 (GPC with polystyrene calibration). The polymer was found tohave p-(1-methoxyethoxy)styrene unit and p-hydroxystyrene unit in amolar ratio of ca. 92:8 based on ¹ HNMR.

REFERENCE EXAMPLE 13 Synthesis ofN-trifluoromethanesulfonyloxybicyclo[2,2,1]-hept-5-ene-2,3-dicarboximide

To a solution of trifluoromethanesulfonic anhydride (6.5 g, 23 mmole) inmethylene chloride (20 ml), a solution ofN-hydroxy-bicyclo[2,2,1]-hept-5-ene-2,3-dicarboximide (3.6 g, 20 mmole)and pyridine (1.6 g) in methylene chloride (10 ml) was added dropwise at0°-5° C. and continued to stir for 15 minutes at the same temperature.The reaction mixture was washed with H₂ O (20 ml×3), dried overanhydrous MgSO₄ and evaporated. The residue was recrystallized fromethanol to give 6.1 g ofN-trifluoromethanesulfonyloxy-bicyclo-[2,2,1]-hept-5-ene-2,3-dicarboximideas white needles. m.p. 89°-90° C.

¹ HNMR δppm (CDCl₃): 1.52 (1H, d, J=9 Hz), 1.79 (1H, d, J=9 Hz), 3.36(2H, s), 3.48 (2H, s), 6.16 (2H, s).

IR (KBr-disk) νcm⁻¹ : 1757 (C═O), 1159 (SO₂).

REFERENCE EXAMPLE 14 Synthesis of dimethylphenylsulfoniumtrifluoromethanesulfonate

To a solution of thioanisole (2.48 g, 20 mmole) in methylene chloride(20 ml), methyl trifluoromethanesulfonate (3.28 g, 20 mmole) was addeddropwise at 10° C. or below, and the mixture was refluxed for 2 hourswith stirring. After cooling, the reaction solution was poured inton-hexane (75 ml), and the precipitate was filtered, washed with n-hexaneand dried. The resultant crude solid (5.35 g) was recrystallized fromiso-propanol to give 4.8 g of dimethylphenylsulfoniumtrifluoromethanesulfonate as white leaflets. m.p. 106.0°-107.2° C.

¹ HNMR δppm (CDCl₃): 3.00 (6H, s, CH₃ ×2), 7.32 (2H, t, J=7 Hz), 7.42(1H, t, J=7 Hz), 7.68 (2H, d, J=7 Hz).

IR (KBr-disk) νcm⁻¹ : 3023, 2947, 1451, 1426, 1254, 1228, 1154.

EXAMPLE 1

A photoresist material of the following composition was prepared:

    ______________________________________                                        Poly(p-1-ethoxyethoxystyrene/p-hydroxystyrene/                                                          5.0 g                                               p-tert-butoxystyrene [Polymer of Synthesis                                    Example 3]                                                                    Bis(cyclohexylsulfonyl)diazomethane                                                                     0.3 g                                               Propylene glycol monomethyl ether                                                                       19.7 g                                              acetate                                                                       ______________________________________                                    

The above resist material was spin coated on each of the threesubstrates (silicon wafers) and prebaked on a hot plate at 90° C. for 90seconds to form a 1.0 μm thick resist film. Then the whole wafer surfacewas exposed by a contact exposure machine (provided with a band passfilter allowing selective passage of light with a wavelength of around250 nm alone) for 30 seconds, 60 seconds and 90 seconds for therespective substrates, followed by postbaking on a 100° C. hot plate for90 seconds. ¹ HNMR analysis identified the polymer in each of theexposed resist films as a copolymer having p-hydroxystyrene unit andp-tert-butoxystyrene unit in a ratio of approximately 9:1, with nop-1-ethoxyethoxystyrene unit detected. It was thus confirmed that1-ethoxyethoxy group alone was selectively eliminated by the chemicalamplifying action of the exposure-generated acid, with p-tert-butylgroup undergoing no chemical amplification.

EXAMPLE 2

A photoresist material of the following composition was prepared:

    ______________________________________                                        Poly(p-1-ethoxyethoxystyrene/p-hydroxystyrene/                                                          5.0 g                                               styrene) [Polymer of Synthesis                                                Example 2]                                                                    Bis(1,1-dimethylethylsulfonyl)diazomethane                                                              0.3 g                                               Propylene glycol monomethyl ether acetate                                                               14.7 g                                              ______________________________________                                    

A pattern forming process using the above resist material is explainedwith reference to FIGS. 1A-1C. Above resist material 2 was spin coatedon a semiconductor substrate 1 and prebaked on a hot plate at 90° C. for90 seconds to form a 1.0 μm thick resist film (FIG. 1A). This resistfilm was selectively exposed to 248.4 nm KrF excimer laser (NA 0.50)light 3 through a mask 4 (FIG. 1B). The exposed resist film waspostbaked on a 100° C. hot plate for 90 seconds and then developed withan alkaline developing solution (2.38% tetramethylammonium hydroxidesolution) for 60 seconds, whereby the exposed portion alone of theresist film was dissolved away to form a positive pattern 2a (FIG. 1C).The thus obtained positive pattern had a rectangular shape and showed a0.22 μm line and space resolving performance. Exposure dose in the aboveprocess was approximately 18 mJ/cm².

Change of pattern size with time during the period from exposure tillheat treatment (post-exposure-baking) was measured. 0.22 μm line andspace could be resolved quite normally even after the lapse of 8 hoursfrom exposure.

Also, in case the resist material of the present invention was used,good mask linearity was maintained up to 0.25 μm as shown in FIG. 2. Inthe case of defocus exposure, no deterioration of shape occurred till±0.8 μm for the 0.3 μm line and space, and a satisfactory focus margincould be obtained. The pattern side wall was also smooth and no scum wasobserved.

When the same pattern forming operation as described above was conductedafter keeping the resist material in storage at 23° C. for one month, a0.22 μm line-and-space positive pattern could be resolved at the sameexposure energy, indicating good storage stability of this resistmaterial.

EXAMPLES 3-16

Photoresist materials of the compositions shown in Tables 1-4 wereprepared.

                  TABLE 1                                                         ______________________________________                                        Example Poly(p-1-ethoxyethoxystyrene/p-                                                                      5.0 g                                          3       hydroxystyrene/p-methylstyrene)                                               [Polymer of Synthesis Example 1]                                              1-Acetyl-1-(1-methylethylsulfonyl)-                                                                  0.6 g                                                  diazomethane                                                                  Propylene glycol monomethyl                                                                          14.4 g                                                 ether acetate                                                         Example Poly(p-1-methoxy-1-methylethoxy-                                                                     5.0 g                                          4       styrene/p-hydroxystyrene/p-                                                   tert-butoxystyrene [Polymer of                                                Slynthesis Example 4]                                                         Bis(1-methylsulfonyl)- 0.6 g                                                  diazomethane                                                                  Propylene glycol monomethyl                                                                          14.4 g                                                 ether acetate                                                         Example Poly(p-1-ethoxyethoxystyrene/p-                                                                      5.0 g                                          5       hydroxystyrene/p-methoxystyrene)                                              [Polymer of Synthesis Example 5]                                              Bis(1,1-dimethylethylsulfonyl)-                                                                      0.6 g                                                  diazomethane                                                                  Propylene glycol monomethyl                                                                          14.4 g                                                 ether acetate                                                         Example Poly)p-1-benzyloxy-1-methylethoxy-                                                                   5.0 g                                          6       styrene/p-hydroxystyrene/p-tert-                                              butoxystyrene [Polymer of                                                     Synthesis Example 6]                                                          1-Diazo-1-methylsulfonyl-4-                                                                          0.7 g                                                  phenylbutane-2-one                                                            Methyl 3-methoxypropionate                                                                           17.3 g                                         ______________________________________                                    

                  TABLE 2                                                         ______________________________________                                        Example Poly(p-1-ethoxyethoxystyrene/p-                                                                      5.0 g                                          7       hydroxystyrene/p-tert-                                                        butoxystyrene)                                                                Bis(cyclohexylsulfonyl)                                                                              0.5 g                                                  diazomethane                                                                  9-Diazo-10-phenanthrone                                                                              0.1 g                                                  [Ultraviolet absorbent of                                                     Reference Example 5]                                                          Propylene glycol monomethyl ether                                                                    14.4 g                                                 acetate                                                               Example Poly(p-1-ethoxyethoxystyrene/p-                                                                      5.0 g                                          8       hydroxystyrene/styrene)                                                       1-Diazo-1-cyclohexylsulfonyl-                                                                        0.7 g                                                  3,3-dimethyl-2-butanone                                                       1-Diazo-2-tetralone [Ultraviolet                                                                     0.1 g                                                  absorbent of Reference Example 6]                                             Ethyl lactate          17.2 g                                         Example Poly(p-1-methoxy-1-methylethoxy-                                                                     5.0 g                                          9       styrene/p-hydroxystyrene/p-tert-                                              butoxystyrene)                                                                Bis(cyclohexylsulfonyl)-                                                                             0.7 g                                                  dioazomethane                                                                 2-Diazo-1-tetralone [Ultraviolet                                                                     0.1 g                                                  absorbent of Reference                                                        Example 7]             14.2 g                                                 propylene glycol monomethyl                                                   ether acetate                                                         ______________________________________                                    

                  TABLE 3                                                         ______________________________________                                        Example Poly(p-1-methoxyethoxystyrene/                                                                       5.0 g                                          10      p-hydroxystyrene/p-chlorostyrene)                                             [Polymer of Synthesis Example 7]                                              1-Diazo-1-methylsulfonyl-4-                                                                          0.6 g                                                  phenylbutan-2-one                                                             Propylene glycol monomethyl                                                                          15.4 g                                                 ether acetate                                                         Example Poly(p-1-ethoxyethoxystyrene/p-                                                                      5.0 g                                          11      hydroxystyrene/p-methoxystyrene)                                              Bis(1,1-dimethylethylsulfonyl)-                                                                      0.5 g                                                  diazomethane                                                                  9-Diazofluorene [Ultraviolet                                                                         0.1 g                                                  absorbent of Reference Example 8]                                             Methyl 3-methxypropionate                                                                            17.4 g                                         Example Poly(p-1-ethoxyethoxystyrene/p-                                                                      5.0 g                                          12      hydroxystyrene/p-tert-butoxystyrene                                           Bis(cyclohexylsulfonyl)diazomethane                                                                  0.7 g                                                  9-(2-Methoxyethoxy)methylanthracene                                                                  0.1 g                                                  [Ultraviolet absorbent of                                                     Reference Example 9]                                                          Propylene glycol monomethyl                                                                          14.2 g                                                 ether acetate                                                         Example Poly(p-1-ethoxyethoxystyrene/p-                                                                      5.0 g                                          13      hydroxystyrene/styrene)                                                       1-Acetyl-1-(1-methylethylsulfonyl)-                                                                  0.6 g                                                  diazomethane                                                                  9-Diazo-10-phenanthrone                                                                              0.1 g                                                  Ethyl lactate          17.3 g                                         ______________________________________                                    

                  TABLE 4                                                         ______________________________________                                        Example Poly(p-1-ethoxyethoxystyrene/p-                                                                      5.0 g                                          14      hydroxystyrene/p-methylstyrene)                                               Bis(1,1-dimethylethylsulfonyl)-                                                                      0.6 g                                                  diazomethane                                                                  9-(2-Methoxyethoxy)methylanthracene                                                                  0.1 g                                                  propylene glycol monomethyl                                                                          14.3 g                                                 ether acetate                                                         Example Poly(p-1-ethoxyethoxystyrene/p-                                                                      5.0 g                                          15      hydroxystyrene/p-tert-                                                        butoxystyrene)                                                                Bis(cyclohexylsulfonyl)diazomethane                                                                  0.7 g                                                  9-(2-Methoxyethoxy)methylanthracene                                                                  0.1 g                                                  propylene glycol monomethyl                                                                          14.2 g                                                 ether acetate                                                         Example Poly(p-1-methoxy-1-methylethoxy-                                                                     5.0 g                                          16      styrene/p-hydroxystyrene/p-tert-                                              butoxystyrene)                                                                1-Diazo-1-methylsulfonyl-4-                                                                          0.6 g                                                  phenylbutan-2-one                                                             Dimethylphenylsulfonium                                                                              0.1 g                                                  trifluoromethanesulfonate                                                     [Photoacid generator of Reference                                             Example 14]                                                                   9-(2-Methoxyethoxy)methyl-                                                                           0.1 g                                                  anthracene                                                                    Propylene glycol monomethyl                                                                          14.4 g                                                 ether acetate                                                         ______________________________________                                    

Using the above resist materials, patterns were formed according to thesame process as Example 2. The results are shown in Table 5.

                                      TABLE 5                                     __________________________________________________________________________              Time from exposure to heat treatment                                          and resolving performance (μm L/S)                                    Exposure                                                                           Immediately after  Mask Storage                                     Example                                                                            (mJ/cm.sup.2)                                                                      exposure 30 min.                                                                            8 hr.                                                                              linearity                                                                          stability                                   __________________________________________________________________________     3   18   0.22     0.22 0.22 Good Good                                         4   28   0.24     0.24 0.24 Good Good                                         5   36   0.24     0.24 0.24 Good Good                                         6   18   0.24     0.24 0.24 Good Good                                         7   26   0.22     0.22 0.22 Good Good                                         8   33   0.22     0.22 0.22 Good Good                                         9   35   0.24     0.24 0.24 Good Good                                        10   17   0.24     0.24 0.24 Good Good                                        11   40   0.24     0.24 0.24 Good Good                                        12   33   0.22     0.22 0.22 Good Good                                        13   26   0.22     0.22 0.22 Good Good                                        14   33   0.22     0.22 0.22 Good Good                                        15   35   0.22     0.22 0.22 Good Good                                        16   16   0.24     0.24 0.24 Good Good                                        __________________________________________________________________________

As is seen from Table 5, in any of Examples 3-16, a positive patterncould be formed as in Example 2, and the 0.22-0.24 μm line and spacecould be resolved normally even after the lapse of 8 hours from exposurein the process from exposure to heat treatment (post-exposure-baking) asin Example 2. Also, a focus margin above ±0.8 μm could be obtained for0.30 μm line and space, and good mask linearity was maintained up to0.25 μm.

Further, any of the resist materials according to Examples 3-16 showedgood storage stability.

EXAMPLE 17

A photoresist material of the following composition was prepared:

    ______________________________________                                        Poly(p-1-ethoxyethoxystyrene/p-hydroxystyrene/                                                          5.0 g                                               p-tert-butoxystyrene)                                                         Bis(cyclohexylsulfonyl)diazomethane                                                                     0.3 g                                               1,2,3-tris(trifluoromethanesulfonyloxy)                                                                 0.03 g                                              benzene [Photoacid generator of                                               Synthesis Example 12]                                                         Propylene glycol monomethyl ether acetate                                                               19.67 g                                             ______________________________________                                    

Using the above resist material, a pattern was formed in the same manneras described in Example 2. The obtained pattern had a rectangular shapeand showed a 0.22 μm line and space resolution. Exposure applied in thisprocess was approximately 14 mJ/cm².

Change of pattern size during the period from exposure till heattreatment (post-exposure-baking) was made. 0.22 μm line and space couldbe resolved in a satisfactory way even after the lapse of 8 hours fromexposure.

Also, in case the above resist material was used, good mask linearitywas maintained up to 0.25 μm. In the case of defocus exposure, nodeterioration of shape took place till ±0.8 μm for the 0.30 μm line andspace, and a sufficient focus margin was obtained.

The pattern formed by using the above resist material was smooth on itsside wall. Also, because of sufficient supply of acid along the fulllength of resist down to the bottom portion thereof, no tails and scumswere observed at the end of the pattern as shown in FIG. 3. Further,when a pattern was formed in the same manner as described above afterkeeping the resist material in storage at 23° C. for one month, a 0.22μm line and space positive pattern could be resolved at the sameexposure to show good storage stability of the resist material.

EXAMPLES 18-29

Photoresist materials of the compositions shown in Tables 6-9 wereprepared.

                  TABLE 6                                                         ______________________________________                                        Example Poly(p-1-ethoxyethoxystyrene/p-                                                                      5.5 g                                          18      hydroxystyrene/p-tert-                                                        butoxystyrene)                                                                Bis(1,1-dimethylethylsulfonyl)                                                                       0.3 g                                                  diazomethane                                                                  2,3,4-Tris(trifluoromethane-                                                                         0.05 g                                                 sulfonyloxy)acetophenone                                                      [Photoacid generator of                                                       Synthesis Example 13]                                                         Propylene glycol monomethyl                                                                          19.17 g                                                ether acetate                                                         Example Poly(p-1-methoxyethoxystyrene/                                                                       5.0 g                                          19      p-hydroxystyrene/p-tert-                                                      butoxystyrene)                                                                Bis(1,1-dimethylethylsulfonyl)-                                                                      0.3 g                                                  diazomethane                                                                  2,2',4,4'-tetra(trifluoro-                                                                           0.05 g                                                 methanesulfonyloxy)-                                                          benzophenone [Photoacid generator                                             of Synthesis Example 14]                                                      Propylene glycol monomethyl                                                                          19.67 g                                                ether acetate                                                         Example Poly(p-1-methoxy-1-methylethoxy-                                                                     5.0 g                                          20      styrene/p-hydroxystyrene/p-tert-                                              butoxystyrene)                                                                1-Diazo-methylsulfonyl-4-                                                                            0.3 g                                                  phenylbutan-2-one                                                             1,2,3-Tris(2,2,2-trifluoroethane-                                                                    0.05 g                                                 sulfonyloxy)benzene [Photoacid                                                generator of Synthesis Example 15]                                            9-(2-Methoxyethoxy)methylanthracene                                                                  0.1 g                                                  Propylene glycol monomethyl                                                                          14.57 g                                                ether acetate                                                         ______________________________________                                    

                  TABLE 7                                                         ______________________________________                                        Example Poly(p-1-ethoxyethoxystyrene/p-                                                                      5.0 g                                          21      hydroxystyrene/p-acetyloxystyrene)                                            [Polymer of Synthesis                                                         Example 8]                                                                    Bis(1,1-dimethylethylsulfonyl)-                                                                      0.3 g                                                  diazomethane                                                                  Diphenyl-p-tolylsulfonium                                                                            0.02 g                                                 perfluorooctane sulfonate                                                     [Photoacid generator of                                                       Synthesis Example 17]                                                         Propylene glycol monomethyl                                                                          14.68 g                                                ether acetate                                                         Example Poly(p-1-ethoxyethoxystyrene/p-                                                                      5.0 g                                          22      hydroxystyrene/p-tetrahydro-                                                  pyranyloxystyrene) [Polymer of                                                Synthesis Example 9]                                                          Bis(1,1-dimethylethylsulfonyl)-                                                                      0.3 g                                                  diazomethane                                                                  2,3,4-tris(2,5-dichlorobenzene-                                                                      0.02 g                                                 sulfonyloxy)acetophenone                                                      [Photoacid generator of                                                       Synthesis Example 16]                                                         Ethyl lactate          14.65 g                                        Example Poly(p-1-ethoxyethoxystyrene/                                                                        5.0 g                                          23      p-hydroxystyrene/p-tert-                                                      butoxycarbonyloxystyrene)                                                     [Polymer of Synthesis                                                         Example 10]                                                                   Bis(cyclohexylsulfonyl)-                                                                             0.3 g                                                  diazomethane                                                                  Triphenylsulfonium trifluoro-                                                                        0.02 g                                                 methanesulfonate [Commercial                                                  product]                                                                      Propylene glycol monomethyl                                                                          14.65 g                                                ether acetate                                                         ______________________________________                                    

                  TABLE 8                                                         ______________________________________                                        Example Poly(p-1-methoxyethoxystyrene/p-                                                                     5.0 g                                          24      hydroxystyrene/tert-butyl vinyl-                                              phenoxyacetate [Polymer of                                                    Synthesis Example 11]                                                         Bis(1-methylethylsulfonyl)-                                                                          0.3 g                                                  diazomethane                                                                  2,3,4-tris(2,5-dichlorobenzene-                                                                      0.03 g                                                 sulfonyloxy)acetophenone                                                      Propylene glycol monomethyl                                                                          14.7 g                                                 ether acetate                                                         Example Poly(p-1-ethoxyethoxystyrene/p-                                                                      5.0 g                                          25      hydroxystyrene/p-tert-butoxy-                                                 styrene)                                                                      Bis(cyclohexylsulfonyl)-                                                                             0.3 g                                                  diazomethane                                                                  Triphenylsulfonium trifluoro-                                                                        0.03 g                                                 methanesulfonate                                                              Propylene glycol monomethyl                                                                          14.7 g                                                 ether acetate                                                         Example Poly(p-1-ethoxyethoxystyrene/p-                                                                      5.0 g                                          26      hydroxystyrene/p-tert-                                                        butoxycarbonyloxystyrene                                                      Bis(1,1-dimethylethylsulfonyl)-                                                                      0.3 g                                                  diazomethane                                                                  Methylsulfonyl-p-toluenesulfonyl-                                                                    0.03 g                                                 diazomethane                                                                  Ethyl lactate          14.8 g                                         ______________________________________                                    

                  TABLE 9                                                         ______________________________________                                        Example Poly(p-1-ethoxyethoxystyrene/p-                                                                      5.5 g                                          27      hydroxystyrene/p-tert-                                                        butoxystyrene)                                                                1-Acetyl-1-(1-methylethylsulfonyl)-                                                                  0.3 g                                                  diazomethane                                                                  Diphenyl-p-tolylsulfonium                                                                            0.03 g                                                 perfluorooctanesulfonate                                                      Propylene glycol monomethyl                                                                          14.2 g                                                 ether acetate                                                         Example Poly(p-1-ethoxyethoxystyrene/p-                                                                      5.0 g                                          28      hydroxystyrene/p-tert-butoxy-                                                 carbonyloxystyrene)                                                           Bis(cyclohexylsulfonyl)                                                                              0.3 g                                                  diazomethane                                                                  Triphenylsuflonium 10- 0.03 g                                                 camphorsulfonate [Photoacid                                                   generator of Synthesis Example 19]                                            Propylene glycol monomethyl                                                                          14.4 g                                                 ether acetate                                                         Example Poly(p-1-ethoxyethoxystyrene/p-                                                                      5.0 g                                          29      hydroxystyrene/p-tert-                                                        butoxystyrene)                                                                Bis(1,1-dimethylethylsulfonyl)                                                                       0.3 g                                                  diazomethane                                                                  Triphenylsulfonium p-  0.03 g                                                 toluenesulfonate [Photoacid                                                   generator of Synthesis                                                        Example 18]                                                                   Propylene glycol monomethyl                                                                          14.4 g                                                 ether acetate                                                         ______________________________________                                    

Using the above resist materials, patterns were formed according to theprocess of Example 2. Results are shown in Table 10.

                                      TABLE 10                                    __________________________________________________________________________              Time from exposure to heat treatment                                          and resolving performance (μm L/S)                                    Exposure                                                                           Immediately after  Mask Storage                                     Example                                                                            (mJ/cm.sup.2)                                                                      exposure 30 min.                                                                            8 hr.                                                                              linearity                                                                          stability                                   __________________________________________________________________________    18   18   0.22     0.22 0.22 Good Good                                        19   30   0.22     0.22 0.22 Good Good                                        20   35   0.24     0.24 0.24 Good Good                                        21   30   0.24     0.24 0.24 Good Good                                        22   35   0.24     0.24 0.24 Good Good                                        23   30   0.24     0.24 0.24 Good Good                                        24   30   0.24     0.24 0.24 Good Good                                        25   28   0.22     0.22 0.22 Good Good                                        26   28   0.22     0.22 0.22 Good Good                                        27   33   0.22     0.22 0.22 Good Good                                        28   25   0.22     0.22 0.22 Good Good                                        29   28   0.24     0.24 0.24 Good Good                                        __________________________________________________________________________

As is seen from Table 10, in any of Examples 18-29, 0.22-0.24 μm lineand space could be resolved normally even after the lapse of 8 hoursfrom start of the operation from exposure till heat treatment(post-exposure-baking) as in Example 2. Also, in case the above resistmaterials were used, good mask linearity was maintained up to 0.25 μm.In the case of defocus exposure, the formed patterns had a smooth sidewall. Further, due to sufficient supply of acid down to the bottomportion of resist, there was observed no scum and tails at the bottomportion of pattern. A focus margin greater than ±0.8 μm was obtained for0.30 μm line and space. Any of the resist materials of Examples 18-29showed satisfactory storage stability.

EXAMPLE 30

A photoresist material of the following composition was prepared:

    ______________________________________                                        Poly(p-1-ethoxyethoxystyrene/p-hydroxystyrene/                                                          5.0 g                                               p-tert-butoxystyrene)                                                         Triphenylsulfonium trifluoromethane                                                                     0.3 g                                               sulfonate                                                                     Propylene glycol monomethyl ether acetat                                                                14.7 g                                              ______________________________________                                    

The above resist material was spin coated on a semiconductor substrateand prebaked on a hot plate at 90° C. for 90 seconds to form a 1.0 μmthick film of resist material. On this resist material film was spincoated a coating material of the following composition to form a0.1-0.15 μm overcoat:

    ______________________________________                                        Polyacrylic acid        2.0 g                                                 Perfluorooctanesulfonic acid                                                                          2.5 g                                                 Fluorine-containing nonionic surfcatant                                                               0.2 g                                                 Water                   95.3 g                                                ______________________________________                                    

Then a pattern was formed in the same way as Example 2. The obtainedpattern was of a rectangular shape and had a 0.22 μm line and spaceresolving power. Exposure dose in the above process was approximately 15mJ/cm². Pattern size was measured with the laspe of time duringoperation from exposure till heat treatment. As it was found, 0.22 μmline and space could be resolved even after the lapse of 8 hours fromexposure. Due to additional use of said aqueous overcoating material,mask linearity was maintained good up to 0.25 μm. There was observed noscum and tails at the pattern bottom. The above resist material alsoshowed good storage stability.

COMPARATIVE EXAMPLES 1-14

By way of comparison, photoresist materials were prepared from theformulations shown in Tables 11-14 and patterns were formed in the samemanner as described in Example 2 using the above photoresist materials.Results are shown in Tables 15-16.

The result (T-shaping) of pattern forming process of Comparative Example1 where the resist material was heat treated (post-exposure-baked) anddeveloped after the lapse of 30 minutes from exposure is shown in FIG.4, and the result (failure to form a pattern) of pattern formingprocesses of Comparative Examples 2 and 3 where heat treatment anddevelopment were carried out after the lapse of 30 minutes formexposure, Comparative Examples 4-8 and 10-14 where heat treatment anddevelopment were conducted after the lapse of 15 minutes from exposureand Comparative Example 9 where heat treatment and development wereconducted after the laspe of 8 hours from exposure, is shown in FIG. 5.

                  TABLE 11                                                        ______________________________________                                        Comp.  Poly(p-tetrahydropyranyloxystyrene/p-                                                                   5.0 g                                        Example                                                                              hydroxystyrene) [Polymer of Reference                                  1      Example 2]                                                                    Bis(cyclohexylsulfonyl)diazomethane                                                                     0.3 g                                               Diethylene glycol dimethyl ether                                                                        14.7 g                                       Comp.  Poly(p-tert-butoxystyene/p-hydroxystyrene                                                               5.0 g                                        Example                                                                              [Polymer of Reference Example 4]                                       2      Bis(cyclohexylsulfonyl)diazomethane                                                                     0.3 g                                               Diethylene glycol dimethyl ether                                                                        14.7 g                                       Comp.  Poly(p-tert-butoxycarbonyloxystyrene/                                                                   5.0 g                                        Example                                                                              p-hydroxystyrene [Polymer of Reference                                 3      Example 3]                                                                    Bis(cyclohexylsulfonyl)diazomthane                                                                      0.3 g                                               Diethylene glycol dimethyl ether                                                                        14.7 g                                       Comp.  Poly(p-tert-butoxycarbonyloxysltyrene/                                                                  5.0 g                                        Example                                                                              p-hydroxystyrene)                                                      4      Triphenylsuflonium trifluoromethane                                                                     0.5 g                                               sulfonate [Commercial product]                                                Propylene glycol monomethyl                                                                             14.5 g                                              ether acetate                                                          Comp.  Poly(p-tetrahydropyranyloxystyrene/                                                                     5.0 g                                        Example                                                                              p-hydroxystyrene)                                                      5      Diphenyliodonium hexafluoro-                                                                            0.3 g                                               phosphate [Commercial product]                                                Diethylene glycol dimethyl ether                                                                        14.7 g                                       ______________________________________                                    

                  TABLE 12                                                        ______________________________________                                        Comp.   Poly(p-tert-butoxystyrene/p-                                                                           5.0 g                                        Example hydroxystyrene)                                                       6       Triphenylsulfonium hexafluorophosphate                                                                 0.3 g                                                Diethylene glycol dimethyl ether                                                                       14.7 g                                       Comp.   Poly(p-tert-butoxyxarbonyloxystyrene/                                                                  5.0 g                                        Example p-hydroxystyrene)                                                     7       Diphenyliodonium hexafluorophosphate                                                                   0.3 g                                                Diethylene glycol dimethyl ether                                                                       14.7 g                                       Comp.   Poly(p-1-ethoxyethoxystyrene/p-                                                                        5.0 g                                        Example hydroxystyrene/styrene [Polymer of                                    8       Synthesis Example 2]                                                          Tris(trichloromethyl)-s-triazine                                                                       1.1 g                                                Trithethanolamine        0.1 g                                                Propylene glycol monomethyl ether                                                                      13.8 g                                               acetate                                                               Comp.   Poly(tert-butyl p-vinylphenoxyacetate/                                                                 5.0 g                                        Example p-hydroxystyrene) [Polymer of Reference                               9       Example 10]                                                                   Bis(cyclohexylsulfonyl)diazomethane                                                                    0.3 g                                                Methyl 3-methoxypropionate                                                                             14.7 g                                       ______________________________________                                    

                  TABLE 13                                                        ______________________________________                                        Comp.   Poly(p-1-ethoxyethoxystyrene/p-                                                                        5.0 g                                        Example hydroxystyrene/p-methylstyrene)                                       10      [Polymer of Synthesis Example 1]                                              Diphenyliodonium hexafluorophosphate                                                                   0.3 g                                                Propylene glycol monomethyl ether                                                                      14.7 g                                               acetate                                                               Comp.   Poly(p-1-ethoxyethoxystyrene/p-                                                                        5.0 g                                        Example hyrdroxystyrene/p-acetyloxystyrene                                    11      [Polymer of Synthesis Example 8]                                              Triphenylsulfonium hexafluorophosphate                                                                 0.3 g                                                Propylene glycol monomethyl ether                                                                      14.7 g                                               acetate                                                               Comp.   Poly(p-1-ethoxyethoxystyrene/p-                                                                        5.0 g                                        Example hydroxystyrene/p-tert-butoxycarbonyloxy-                              12      styrene) [Polymer of Synthesis Example                                        10]                                                                           Diphenyliodonium hexafluorophosphate                                                                   0.3 g                                                Propylene glycol monomethyl ether                                                                      14.7 g                                               acetate                                                               ______________________________________                                    

                  TABLE 14                                                        ______________________________________                                        Comp.   Poly(p-1-ethoxyethoxystyrene/p-                                                                        5.0 g                                        Example hydroxystyrene/p-tert-butoxystyrene                                   13      Tris(trichloromethyl)-s-triazine                                                                       1.2 g                                                Acetamide                0.2 g                                                Propylene glycol monomethyl ether                                                                      13.6 g                                               acetate                                                               Comp.   Poly(p-1-ethoxyethoxystyrene/p-                                                                        5.0 g                                        Example hydroxystyrene/p-tert-butoxy-                                         14      carbonyloxystyrene)                                                           2,6-Dinitrobenzyl p-toluenesulfonate                                                                   0.3 g                                                Propylene glycol monomethyl ether                                                                      14.8 g                                               acetate                                                               ______________________________________                                    

                                      TABLE 15                                    __________________________________________________________________________              Time from exposure to heat treatment and resolving performance                (μm L/S)                                                                   Immediately                                                         Comp.                                                                              Exposure                                                                           after                                                               Example                                                                            mJ/cm.sup.2                                                                        exposure                                                                             15 min.                                                                              30 min.                                                                              1 hr.  8 hr.                                   __________________________________________________________________________    1    30   0.35   0.35   T-shaping                                                                            Unable to                                                                            --                                                                     form pattern                                   2    30   0.35   0.35   Unable to                                                                            --     Unable to                                                       form pattern  form pattern                            3    35   0.35   0.35   Unable to                                                                            --     --                                                              form pattern                                          4    12   0.35   Unable to                                                                            Unable to                                                                            --     --                                                       form pattern                                                                         form pattern                                          5    3    0.35   Unable to                                                                            --     --     --                                                       form pattern                                                 6    3    0.35   Unable to                                                                            --     --     --                                                       form pattern                                                 7    3    0.35   Unable to                                                                            --     --     --                                                       form pattern                                                 8    6    0.40   Unable to                                                                            --     --     --                                                       form pattern                                                 9    32   0.35   0.35   0.35   0.35   Unable to                                                                     form pattern                            __________________________________________________________________________

                                      TABLE 16                                    __________________________________________________________________________              Time from exposure to heat treatment and resolving                            performance (μm L/S)                                                       Immediately                                                         Comp.                                                                              Exposure                                                                           after                                                               Example                                                                            mJ/cm.sup.2                                                                        exposure                                                                              15 min. 30 min.                                                                            1 hr.                                                                             8 hr.                                      __________________________________________________________________________    10   5    0.30    Unable to                                                                             --   --  --                                                           form pattern                                                11   6    0.30    Unable to                                                                             --   --  --                                                           form pattern                                                12   3    0.30    Unable to                                                                             --   --  --                                                           form pattern                                                13   4    0.30    Unable to                                                                             --   --  --                                                           form pattern                                                14   7    0.35    Unable to                                                                             --   --  --                                                           form pattern                                                __________________________________________________________________________

As is seen from Tables 15-16 and FIGS. 4-5, the resist materialsprepared according to the above Comparative Examples are all inferior inresolution to the resist materials using the polymers according to thepresent invention. Also, in case a time of 15-30 minutes or more isrequired for the process from exposure to heat treatment(post-exposure-baking) as in the case of Comparative Examples 1-6, theretakes place "T-shaping" of the pattern or it becomes impossible to forma pattern itself. The resist material of Comparative Example 9 wasincapable of forming a pattern when heat treatment was conducted afterthe lapse of 8 hours from exposure. Further, in the case of the resistmaterial prepared by combining a polymer according to the presentinvention and tris(trichloromethyl)-s-triazine/hydrogen donor, a knownphotoacid generator, no pattern can be formed when 15-30 minutes orlonger time is required for the process from exposure till heattreatment as seen from the result of Comparative Example 13.

In the case of the photoresist materials of Comparative Examples 10-12,when it was tried to form a pattern by following the process of Example2 after leaving the resist materials at 23° C. for one week, bothexposed and non-exposed portions were dissolved in the developingsolution and no pattern could be obtained, indicating poor storagestability of these photoresist materials.

COMPARATIVE EXAMPLE 15

A photoresist material of the following composition was prepared:

    ______________________________________                                        Poly(p-1-ethoxyethoxystyrene/p-                                                                      5.0 g                                                  hydroxystyrene/p-tert-butoxystyrene                                           2-methyl-2-(p-toluenesulfonyl)-                                                                      0.3 g                                                  propiophenone                                                                 Propylene glycol monomethyl                                                                          14.7 g                                                 ether acetate                                                                 ______________________________________                                    

Using the above resist material, pattern formation was carried outaccording to the process of Example 2. Although a 0.22 μm line and spacepositive pattern could be formed at exposure of 16 mJ/cm², the bottomportion of the pattern terminated into tails as shown in FIG. 6, makingthe pattern shape non-conforming. Mask linearity was also poor as shownin FIG. 7. Further, focus margin for 0.30 μm line and space was as smallas ±0.6 μm.

COMPARATIVE EXAMPLE 16

A photoresist material of the following composition was prepared:

    ______________________________________                                        Poly(p-1-ethoxyethoxystyrene/p-                                                                     5.0 g                                                   hydroxystyrene/fumaronitrile)                                                 [Polymer of Reference Example 11]                                             2-cyclohexylcarbonyl-2-(p-                                                                          0.3 g                                                   toluenesulfonyl)propane                                                       Propylene glycol monomethyl                                                                         14.7 g                                                  ether acetate                                                                 ______________________________________                                    

Using the above resist material, pattern formation was carried out inthe same manner as described in Example 2. As a result, a 0.24 μm lineand space positive pattern was formed at exposure of 18 mJ/cm², but thefocus margin for 0.30 μm line and space and mask linearity wereunsatisfactory as in Comparative Example 15.

COMPARATIVE EXAMPLE 17

A photoresist material of the following composition was prepared:

    ______________________________________                                        Poly(p-1-ethoxyethoxystyrene/p-                                                                      6.0 g                                                  hydroxystyrlene) [Polymer of                                                  Reference Example 1]                                                          Bis(cyclohexylsulfonyl)diazomethane                                                                  0.4 g                                                  Diethylene glycol dimethylether                                                                      13.6 g                                                 ______________________________________                                    

Using the above resist material, the pattern forming process of Example2 was carried out. A 0.30 μm line and space positive pattern was formedat exposure of 15 mJ/cm², but scums were observed at the bottom portionof the pattern as shown in FIG. 8. Also, the focus margin for 0.30 μmline and space and mask linearity were unsatisfactory as in ComparativeExample 15.

COMPARATIVE EXAMPLE 18

A photoresist material of the following composition was prepared:

    ______________________________________                                        Poly(p-1-ethoxyethoxystyrene/p-                                                                       6.0 g                                                 hydroxystyrene) [Polymer of Reference                                         Example 12]                                                                   Triphenylsulfonium trifluoromethane-                                                                  0.3 g                                                 sulfonate                                                                     Propylene glycol monomethyl ether                                                                     13.7 g                                                acetate                                                                       ______________________________________                                    

Using the above resist material, the process of Example 2 was carriedout for forming a pattern. Film exfoliation occurred during developmentdue to imperfect adhesion to the substrate, making it unable to form apattern. Even if a pattern could be formed, the top of the resist filmwas rounded and tails were formed at the bottom portion of the patternas shown in FIG. 9 due to poor heat resistance of said resist material.

COMPARATIVE EXAMPLE 19

A photoresist material of the following composition was prepared:

    ______________________________________                                        Poly(p-1-ethoxyethoxystyrene/p-                                                                      5.0 g                                                  hydroxystyrene/p-tert-                                                        butoxycarbonyloxystyrene)                                                     N-trifluoromethanesulfonyloxy-                                                                       0.3 g                                                  bicyclo[2,2,2]-hepto-5-ene-2,3                                                dicarboxyimide [Photoacid generator                                           of Reference Example 13]                                                      Propylene glycol monomethyl                                                                          14.7 g                                                 ether acetate                                                                 ______________________________________                                    

Using the above resist material, pattern formation was conductedaccording to the procedure of Example 2. A 0.30 μm line and spacepositive pattern was formed at exposure of 9 mJ/cm². However, when thesame pattern forming operation was carried out after 3-day preservationof the resist material at 23° C., although a 0.40 μm line and spacepositive pattern was formed at exposure of 4 mJ/cm², the 0.30 μm lineand space could not be resolved. Also, a change of sensitivity wasobserved.

COMPARATIVE EXAMPLE 20

A photoresist material of the following composition was prepared:

    ______________________________________                                        Poly(p-1-ethoxyethoxystyrene/                                                                      6.0 g                                                    p-hydroxystyrene) [Polymer of                                                 Reference Example 1]                                                          Triphenylsulfonium trifluoro-                                                                      0.3 g                                                    methanesulfonate                                                              Propylene glycol monomethyl                                                                        13.7 g                                                   ether acetate                                                                 ______________________________________                                    

Using the above resist material, the process of Example 2 was repeated.A 0.30 μm line and space positive pattern was formed at exposure of 6mJ/cm², but when heating and development were performed after the lapseof one hour from exposure, the size of the pattern formed was more than10% smaller than that formed when heating and development were conductedimmediately after exposure.

As is appreciated from the foregoing explanation, when a resist materialcomprising a polymer according to the present invention is used forexposure with a light source of 300 nm or less, such as deep ultravioletlight or KrF excimer laser light (248.4 nm), it is possible to obtain afine pattern having a very high resolving performance, capable ofmaintaining its size unchanged throughout the period of operation fromexposure till heat treatment (post-exposure-baking) and having a goodshape with a practical size of quarter-micron order with a large focaldepth tolerance. Mask linearity is also improved. Therefore, the presentinvention is of great worth for ultra-fine pattern formation insemiconductor industries.

The resist material using a polymer according to the present inventionis particularly useful for pattern formation by use of deep ultravioletlight or KrF excimer laser light, but it can also as well be applied topattern formation using i-line (365 nm), electron beams, soft X-rays orthe like.

What is claimed is:
 1. A pattern forming process comprising the stepsof: coating a resist material comprising:(a) a polymer represented bythe formula (1): ##STR51## wherein R¹ is a hydrogen atom or a methylgroup; R² and R³ are independently a hydrogen atom, a straight-chain,branched or cyclic alkyl group having 1-6 carbon atoms, a straight-chainor branched haloalkyl group having 1-6 carbon atoms, or a phenyl group,provided that R² and R³ are not a hydrogen atom at the same time, or R²and R³ may combine to form a methylene chain having 2-5 carbon atoms; R⁴is a straight-chain, branched or cyclic alkyl group having 1-10 carbonatoms, a straight-chain, branched or cyclic haloalkyl group having 1-6carbon atoms, an acetyl group or an aralkyl group; R⁵ is a hydrogenatom, a halogen atom, a straight-chain, branched or cyclic alkyl grouphaving 1-6 carbon atoms, a straight-chain, branched or cyclic alkoxygroup having 1-6 carbon atoms, a tetrahydropyranyloxy group, atetrahydrofuranyloxy group, a tert-butoxycarbonyloxy group, atert-butoxycarbonylmethoxy group or an acetyloxy group; and k, r and mare independently an integer of 1 or more, provided that0.10≦(k+m)/(k+r+m)≦0.90 and 0.01≦m/(k+r+m)≦0.25, (b) at least onephotosensitive compound capable of generating an acid upon exposure tolight, selected from the group consisting of the photosensitivecompounds represented by the following formula (2), the photosensitivecompounds represented by the following formula (3), the photosenstivecompounds represented by the following formula (4), the photosensitivecompounds represented by the following formula (5), the photosensitivecompounds represented by the following formula (6) and thephotosensitive compounds represented by the following formula (7):##STR52## wherein R⁶ and R⁷ are independently a straight-chain, branchedor cyclic alkyl group having 1-10 carbon atoms or a haloalkyl grouphaving 1-10 carbon atoms; and Z is a sulfonyl group or a carbonyl group;##STR53## wherein R⁸ is a hydrogen atom, a halogen atom, astraight-chain or branched alkyl group having 1-5 carbon atoms, astraight-chain or branched alkoxy group having 1-5 carbon atoms, or astraight-chain or branched haloalkyl group having 1-5 carbon atoms; andR⁹ is a straight-chain, branched or cyclic alkyl group having 1-10carbon atoms, a haloalkyl group having 1-10 carbon atoms, or a grouprepresented by the formula (a): ##STR54## wherein R¹⁰ is a hydrogenatom, a halogen atom, a straight-chain or branched alkyl group having1-5 carbon atoms, a straight-chain or branched alkoxy group having 1-5carbon atoms, or a straight-chain or branched haloalkyl group having 1-5carbon atoms; and n is 0 or an integer of 1-3; ##STR55## wherein R¹¹ isa hydrogen atom, a halogen atom, a straight-chain or branched alkylgroup having 1-5 carbon atoms, an aralkyl group or a trifluoromethylgroup; and R¹² is a straight-chain, branched or cyclic alkyl grouphaving 1-10 carbon atoms, an aralkyl group, a straight-chain or branchedalkoxy group having 1-5 carbon atoms, a phenyl group or a tolyl group;##STR56## wherein R¹³ is a group represented by the formula (b):##STR57## wherein R¹⁴, R¹⁵ and R¹⁶ are independently a hydrogen atom ora halogen atom; and p is 0 or an integer of 1-3, or a group representedby the formula (c): ##STR58## wherein R¹⁷, R¹⁸, R¹⁹, R²⁰ and R²¹ areindependently a hydrogen atom, a halogen atom, a straight-chain orbranched alkyl group having 1-5 carbon atoms, a straight-chain orbranched alkoxy group having 1-5 carbon atoms, a trifluoromethyl group,a hydroxyl group, a trifluoromethoxy group or a nitro group; ##STR59##wherein R¹³ is as defined above; R²³ is a hydrogen atom, a hydroxylgroup or a group represented by the formula (d):

    R.sup.13 SO.sub.2 O--                                      (d)

wherein R¹³ is as defined above; and R²³ is a straight chain or branchedalkyl group having 1-5 carbon atoms or a group represented by theformula (e): ##STR60## wherein R²⁴ and R³⁰ are independently a hydrogenatom, a halogen atom, a straight-chain or branched alkyl group having1-5 carbon atoms, a straight-chain or branched alkoxy group having 1-5carbon atoms or a group of the formula (d); ##STR61## wherein R²⁵ is astraight-chain or branched alkyl group having 1-4 carbon atoms, a phenylgroup, a substituted phenyl group or an aralkyl group; R²⁶ is a hydrogenatom, a halogen atom or a straight-chain, branched or cyclic alkyl grouphaving 1-6 carbon atoms; R²⁷ is a straight-chain or branchedperfluoroalkyl group having 1-8 carbon atoms, a straight-chain, branchedor cyclic alkyl group having 1-8 carbon atoms, a 1-naphthyl group, a2-naphthyl group, a 10-camphor group, a phenyl group, a tolyl group, a2,5-dichlorophenyl group, a 1,3,4-trichlorophenyl group or atrifluoromethylphenyl group; and (c) a solvent capable of dissolving theabove components (a) and (b) on a substrate; heating and then exposingthe resist film to light with a wavelength of 300 nm or less; anddeveloping the exposed resist film with a developing solution.
 2. Aprocess according to claim 1, which further comprises heating the resistfilm after exposure to the light.